fix: set required compiler flags for osdi

configure.ac

@@ -1156,13 +1156,49 @@ if test "x$enable_xspice" = xyes; then
     AC_SUBST([VIS_CFLAGS])
 else
     XSPICEINIT="*"
+    if test "x$enable_osdi" = xyes; then\
+        case $host_os in
+            *mingw* | *msys* | *cygwin* | *solaris* )
+                XSPICEDLLIBS=""
+                ;;
+            * )
+                XSPICEDLLIBS="-ldl"
+                ;;
+        esac
+    fi
 fi
+
 AC_SUBST([XSPICEINIT])
 AC_SUBST([XSPICEDLLIBS])
 
 AM_CONDITIONAL([XSPICE_WANTED], [test "x$enable_xspice" = xyes])
 
+
+
 if test "x$enable_osdi" = xyes; then
+    AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+    [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+    AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+    AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+      ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+      _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+      AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+        [AS_VAR_SET(CACHEVAR,[yes])],
+        [AS_VAR_SET(CACHEVAR,[no])])
+      _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+    AS_VAR_IF(CACHEVAR,yes,
+      [m4_default([$2], :)],
+      [m4_default([$3], :)])
+    AS_VAR_POPDEF([CACHEVAR])dnl
+    ])dnl AX_CHECK_COMPILE_FLAGS
+
+    AX_CHECK_COMPILE_FLAG([-std=c11], [
+      CFLAGS="$CFLAGS -std=c11"
+      LDLAGS="$LDLAGS -std=c11"
+    ], [
+      echo "C compiler cannot compile C11 code"
+      exit -1
+    ])
     AC_MSG_RESULT([OSDI features included])
     AC_DEFINE([OSDI], [1], [The OSDI enhancements])
 fi

src/Makefile.am

@@ -165,9 +165,9 @@ ngspice_LDADD += \
 	xspice/evt/libevtxsp.la \
 	xspice/enh/libenhxsp.la \
 	xspice/ipc/libipcxsp.la \
-	xspice/idn/libidnxsp.la \
-	@XSPICEDLLIBS@
+	xspice/idn/libidnxsp.la 
 endif
+ngspice_LDADD += @XSPICEDLLIBS@
 
 ngspice_LDADD += \
 	frontend/parser/libparser.la \
@@ -452,9 +452,9 @@ libspice_la_LIBADD += \
 	xspice/evt/libevtxsp.la \
 	xspice/enh/libenhxsp.la \
 	xspice/ipc/libipcxsp.la \
-	xspice/idn/libidnxsp.la \
-	@XSPICEDLLIBS@
+	xspice/idn/libidnxsp.la 
 endif
+libspice_la_LIBADD += @XSPICEDLLIBS@
 
 libspice_la_LIBADD += \
 	frontend/parser/libparser.la \
@@ -576,9 +576,9 @@ libngspice_la_LIBADD += \
 	xspice/evt/libevtxsp.la \
 	xspice/enh/libenhxsp.la \
 	xspice/ipc/libipcxsp.la \
-	xspice/idn/libidnxsp.la \
-	@XSPICEDLLIBS@
+	xspice/idn/libidnxsp.la 
 endif
+libngspice_la_LIBADD += @XSPICEDLLIBS@
 
 libngspice_la_LIBADD += \
 	frontend/parser/libparser.la \