build: make configure relocatable (out-of-tree)

Enable `mkdir build; cd build; ../configure` to run entirely in the build
directory, with generated config landing there instead of in the source
tree.  This is the autoconf-layer groundwork for a full VPATH build; the
make layer (defs.mak/rules.mak VPATH support, per-dir orchestration) is
still to come, so an out-of-tree `make` is not yet expected to work.

Changes:

* configure (wrapper): run the generated config.status in the *current*
  directory with --srcdir pointing back at the source tree (instead of
  `cd scripts`), so outputs land in the build dir.  Uses an absolute
  basedir so any build-dir location works, not just a subdir of srcdir.

* scripts/configure.in:
  - AC_CONFIG_AUX_DIR(.) -> AC_CONFIG_AUX_DIR(scripts).  Once srcdir
    resolves to the true top (scripts' parent, where rules.mak lives),
    autoconf searches for install-sh/config.sub/... relative to srcdir;
    "." pointed at the wrong place and out-of-tree configure died with
    "cannot find install-sh".
  - Name the .in templates explicitly
    (defs.mak:scripts/defs.mak.in, scripts/makedbh:scripts/makedbh.in)
    so config.status finds them from a separate build dir.  defs.mak is
    written to the build top; makedbh under build/scripts/ to match
    ${SCRIPTS}/makedbh.
  - Drop the trailing `cp defs.mak ..`; defs.mak is now generated in the
    build top directly, and from a build dir the copy would clobber the
    source tree's defs.mak.

* scripts/configure: regenerated with autoconf 2.69.

Verified: out-of-tree `../configure` completes rc=0, writes defs.mak /
scripts/makedbh / config.status into the build dir, records
srcdir=<source top>, and leaves the source tree's tracked files and
generated defs.mak/makedbh untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

configure

@@ -9,5 +9,9 @@
 # script itself.  It also sets up CFLAGS without the default optimizer
 # flag (-O2).
 
-basedir=$(dirname "$0")
-( CFLAGS=${CFLAGS:-"-g"}; export CFLAGS; cd "${basedir}/scripts" ; ./configure "$@" )
+# Run the generated config.status in the *current* directory (which may be a
+# separate build directory), with --srcdir pointing back at the source tree, so
+# that generated files (defs.mak, makedbh, ...) land in the build directory
+# rather than in the source tree.
+basedir=$(cd "$(dirname "$0")" && pwd)
+( CFLAGS=${CFLAGS:-"-g"}; export CFLAGS; exec "${basedir}/scripts/configure" --srcdir="${basedir}" "$@" )

scripts/configure

@@ -734,7 +734,6 @@ infodir
 docdir
 oldincludedir
 includedir
-runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -843,7 +842,6 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
-runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE}'
@@ -1096,15 +1094,6 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
-  -runstatedir | --runstatedir | --runstatedi | --runstated \
-  | --runstate | --runstat | --runsta | --runst | --runs \
-  | --run | --ru | --r)
-    ac_prev=runstatedir ;;
-  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
-  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
-  | --run=* | --ru=* | --r=*)
-    runstatedir=$ac_optarg ;;
-
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1242,7 +1231,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir runstatedir
+		libdir localedir mandir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1395,7 +1384,6 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
-  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -2598,7 +2586,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 ac_aux_dir=
-for ac_dir in . "$srcdir"/.; do
+for ac_dir in scripts "$srcdir"/scripts; do
   if test -f "$ac_dir/install-sh"; then
     ac_aux_dir=$ac_dir
     ac_install_sh="$ac_aux_dir/install-sh -c"
@@ -2614,7 +2602,7 @@ for ac_dir in . "$srcdir"/.; do
   fi
 done
 if test -z "$ac_aux_dir"; then
-  as_fn_error $? "cannot find install-sh, install.sh, or shtool in . \"$srcdir\"/." "$LINENO" 5
+  as_fn_error $? "cannot find install-sh, install.sh, or shtool in scripts \"$srcdir\"/scripts" "$LINENO" 5
 fi
 
 # These three variables are undocumented and unsupported,
@@ -9308,9 +9296,9 @@ MAKE_CAIRO=$usingCairo
 MAKE_READLINE=$use_bundled_readline
 
 
-ac_config_files="$ac_config_files defs.mak"
+ac_config_files="$ac_config_files defs.mak:scripts/defs.mak.in"
 
-ac_config_files="$ac_config_files makedbh"
+ac_config_files="$ac_config_files scripts/makedbh:scripts/makedbh.in"
 
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
@@ -10019,8 +10007,8 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 for ac_config_target in $ac_config_targets
 do
   case $ac_config_target in
-    "defs.mak") CONFIG_FILES="$CONFIG_FILES defs.mak" ;;
-    "makedbh") CONFIG_FILES="$CONFIG_FILES makedbh" ;;
+    "defs.mak") CONFIG_FILES="$CONFIG_FILES defs.mak:scripts/defs.mak.in" ;;
+    "scripts/makedbh") CONFIG_FILES="$CONFIG_FILES scripts/makedbh:scripts/makedbh.in" ;;
 
   *) as_fn_error $? "invalid argument: \`$ac_config_target'" "$LINENO" 5;;
   esac
@@ -10441,7 +10429,7 @@ which seems to be undefined.  Please make sure it is defined" >&2;}
 
 
   case $ac_file$ac_mode in
-    "makedbh":F) chmod +x makedbh ;;
+    "scripts/makedbh":F) chmod +x scripts/makedbh ;;
 
   esac
 done # for ac_tag
@@ -10591,4 +10579,3 @@ echo
 echo "-----------------------------------------------------------"
 echo
 
-cp defs.mak ..

scripts/configure.in

@@ -4,7 +4,12 @@ dnl Use autoconf 2.52 or newer.
 AC_INIT(magic,, magic-hackers@csl.cornell.edu)
 AC_PREREQ(2.52)
 AC_CONFIG_SRCDIR(rules.mak)
-AC_CONFIG_AUX_DIR(.)
+dnl configure.in lives in scripts/, but the source root is its parent (that is
+dnl where rules.mak is, so srcdir resolves there).  The aux scripts (install-sh,
+dnl config.sub, config.guess, missing, mkinstalldirs) live in scripts/, which is
+dnl "scripts" relative to that srcdir -- not ".".  Using "." breaks out-of-tree
+dnl configure with "cannot find install-sh".
+AC_CONFIG_AUX_DIR(scripts)
 
 AC_CANONICAL_SYSTEM
 
@@ -1971,8 +1976,12 @@ AC_SUBST(MAKE_GLU,      [$usingGLU])
 AC_SUBST(MAKE_CAIRO,    [$usingCairo])
 AC_SUBST(MAKE_READLINE, [$use_bundled_readline])
 
-AC_CONFIG_FILES([defs.mak])
-AC_CONFIG_FILES([makedbh], [chmod +x makedbh])
+dnl Name the .in templates explicitly (relative to srcdir) so config.status can
+dnl find them when run from a separate build directory.  Outputs land in the
+dnl build directory (config.status' CWD): defs.mak at the build top, makedbh
+dnl under build/scripts/ (matching ${SCRIPTS}/makedbh = ${MAGICDIR}/scripts).
+AC_CONFIG_FILES([defs.mak:scripts/defs.mak.in])
+AC_CONFIG_FILES([scripts/makedbh:scripts/makedbh.in], [chmod +x scripts/makedbh])
 AC_OUTPUT
 
 dnl 
@@ -2087,5 +2096,6 @@ echo
 echo "-----------------------------------------------------------"
 echo
 
-dnl Put "defs.mak" in the top-level directory
-cp defs.mak ..
+dnl "defs.mak" is now generated directly into the build top (config.status'
+dnl CWD), so the old `cp defs.mak ..` is gone -- from a separate build directory
+dnl it would clobber the source tree's copy.