K&R calma: remove system header time() K&R style prototype

time.h has existed since C89 so is a standard header expected
to always be available.

sys/time.h was an optional header that historically only some
platforms provided.

If there is a conflict on specific platforms it is better to
'#if !defined()' that specific niche platform with the problem
if both headers are included in the same compile unit.  But I
don't think this is a problem in modern times.

So this results in a resolution that removes #ifdef around
time.h and the detection by configure for the availabiltiy
of sys/time.h.

K&R obsolete syntax removal for C23 compatibility series

scripts/configure.in

@@ -150,6 +150,9 @@ AC_CHECK_HEADERS(param.h)
 dnl Check for <paths.h>
 AC_CHECK_HEADERS(paths.h)
 
+dnl Check for <sys/time.h>
+AC_CHECK_HEADERS(sys/time.h)
+
 dnl Check for va_copy
 AC_CACHE_CHECK([for va_copy], ac_cv_c_va_copy,
  AC_TRY_LINK(