configure: use XC_CONFIGURE_PREAMBLE early checks

Some basic checks we make were placed early enough in generated
configure script when using autoconf 2.5X versions. Newer autoconf
versions expand these checks much further into the configure script,
rendering them useless. Using XC_CONFIGURE_PREAMBLE fixes placement
of early intended checks across all our autoconf supported versions.

configure.ac

@@ -4,6 +4,7 @@ dnl Version not hardcoded here. Fetched later from ares_version.h
 AC_INIT([c-ares], [-],
   [c-ares mailing list: http://cool.haxx.se/mailman/listinfo/c-ares])
 
+XC_OVR_ZZ40
 XC_OVR_ZZ50
 XC_OVR_ZZ60
 CARES_OVERRIDE_AUTOCONF
@@ -20,8 +21,6 @@ CARES_CHECK_OPTION_WERROR
 CARES_CHECK_OPTION_CURLDEBUG
 CARES_CHECK_OPTION_SYMBOL_HIDING
 
-CARES_CHECK_PATH_SEPARATOR_REQUIRED
-
 dnl SED is mandatory for configure process and libtool.
 dnl Set it now, allowing it to be changed later.
 AC_PATH_PROG([SED], [sed], [not_found],

m4/cares-override.m4

@@ -2,7 +2,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 7
+# serial 8
 
 dnl CARES_OVERRIDE_AUTOCONF
 dnl -------------------------------------------------
@@ -74,18 +74,3 @@ choke me
 #endif
 ], [return $1 ();])])
 
-dnl Override Autoconf's PATH_SEPARATOR check
-dnl -------------------------------------------------
-dnl This is done to ensure that the same check is
-dnl used across different Autoconf versions and to
-dnl allow us to use this macro early enough in the
-dnl configure script.
-
-m4_defun([_AS_PATH_SEPARATOR_PREPARE],
-[CARES_CHECK_PATH_SEPARATOR
-m4_define([$0],[])])
-
-m4_defun([_LT_AC_LIBTOOL_SYS_PATH_SEPARATOR],
-[CARES_CHECK_PATH_SEPARATOR
-m4_define([$0],[])])
-

m4/cares-system.m4

@@ -1,83 +0,0 @@
-#***************************************************************************
-# $Id$
-#
-# Copyright (C) 2008 - 2009 by Daniel Stenberg et al
-#
-# Permission to use, copy, modify, and distribute this software and its
-# documentation for any purpose and without fee is hereby granted, provided
-# that the above copyright notice appear in all copies and that both that
-# copyright notice and this permission notice appear in supporting
-# documentation, and that the name of M.I.T. not be used in advertising or
-# publicity pertaining to distribution of the software without specific,
-# written prior permission.  M.I.T. makes no representations about the
-# suitability of this software for any purpose.  It is provided "as is"
-# without express or implied warranty.
-#
-#***************************************************************************
-
-# File version for 'aclocal' use. Keep it a single number.
-# serial 3
-
-
-dnl CARES_CHECK_PATH_SEPARATOR
-dnl -------------------------------------------------
-dnl Check and compute the path separator for us. This
-dnl path separator is the symbol used to diferentiate
-dnl or separate paths inside the PATH environment var.
-
-AC_DEFUN([CARES_CHECK_PATH_SEPARATOR], [
-  if test -z "$cares_cv_PATH_SEPARATOR"; then
-    if test -z "$PATH"; then
-      AC_MSG_ERROR([PATH not set. Cannot continue without PATH being set.])
-    fi
-    dnl Directory count in PATH when using a colon separator.
-    tst_dirs_col=0
-    tst_save_IFS=$IFS; IFS=':'
-    for tst_dir in $PATH; do
-      IFS=$tst_save_IFS
-      test -d "$tst_dir" && tst_dirs_col=`expr $tst_dirs_col + 1`
-    done
-    IFS=$tst_save_IFS
-    dnl Directory count in PATH when using a semicolon separator.
-    tst_dirs_sem=0
-    tst_save_IFS=$IFS; IFS=';'
-    for tst_dir in $PATH; do
-      IFS=$tst_save_IFS
-      test -d "$tst_dir" && tst_dirs_sem=`expr $tst_dirs_sem + 1`
-    done
-    IFS=$tst_save_IFS
-    if test $tst_dirs_sem -eq $tst_dirs_col; then
-      dnl When both counting methods give the same result we do not want to
-      dnl chose one over the other, and consider auto-detection not possible.
-      if test -z "$PATH_SEPARATOR"; then
-        dnl Stop dead until user provides PATH_SEPARATOR definition.
-        AC_MSG_ERROR([PATH_SEPARATOR not set. Cannot continue without it.])
-      fi
-    else
-      dnl Separator with the greater directory count is the auto-detected one.
-      if test $tst_dirs_sem -gt $tst_dirs_col; then
-        tst_auto_separator=';'
-      else
-        tst_auto_separator=':'
-      fi
-      if test -z "$PATH_SEPARATOR"; then
-        dnl Simply use the auto-detected one when not already set.
-        PATH_SEPARATOR="$tst_auto_separator"
-      fi
-    fi
-    cares_cv_PATH_SEPARATOR="$PATH_SEPARATOR"
-  fi
-  AC_SUBST([PATH_SEPARATOR])
-  AC_SUBST([PATH])
-])
-
-
-dnl CARES_CHECK_PATH_SEPARATOR_REQUIRED
-dnl -------------------------------------------------
-dnl Use this to ensure that the path separator check
-dnl macro is only expanded and included once.
-
-AC_DEFUN([CARES_CHECK_PATH_SEPARATOR_REQUIRED], [
-  AC_REQUIRE([CARES_CHECK_PATH_SEPARATOR])dnl
-])
-