Add config/gxx-include-dir.m4 (patch 3/4 for PR 7305)

[Richard Sandiford <rsandifo at redhat dot com>]

Following up from: http://gcc.gnu.org/ml/gcc-patches/2004-11/msg02185.
this patch adds a new config/gxx-include-dir.m4 autoconf fragment
and uses it in the top-level configure script.

Bootstrapped & regression tested on i686-pc-linux-gnu in combination
with patches 1 and 2.  I also checked the same things as before.
OK to install?

Richard


	* configure.in: Include config/gxx-include-dir.m4.  Use
	TL_AC_GXX_INCLUDE_DIR.  Remove some now-redundant AC_SUBSTs.
	* configure: Regenerate.

config/
	* gxx-include-dir.m4: New file.

--- configure.in.2	Thu Nov 25 15:36:35 2004
+++ configure.in	Thu Nov 25 17:02:39 2004
@@ -20,6 +20,7 @@
 
 sinclude(config/acx.m4)
 sinclude(config/gcc-version.m4)
+sinclude(config/gxx-include-dir.m4)
 
 AC_INIT(move-if-change)
 AC_PREREQ(2.13)
@@ -1961,22 +1962,7 @@ fi
 target_configargs="--cache-file=./config.cache --host=${target_alias} --build=${build_alias} ${target_configargs}"
 
 # provide a proper gxx_include_dir.
-# Note, if you change the default, make sure to fix both here and in
-# the gcc and libstdc++-v3 subdirectories.
-# Check whether --with-gxx-include-dir or --without-gxx-include-dir was given.
-case "${with_gxx_include_dir}" in
-  yes)
-    AC_MSG_ERROR([--with-gxx-include-dir=[[dir]] requires a directory])
-    ;;
-  no | "")
-    case "${enable_version_specific_runtime_libs}" in
-      yes) gxx_include_dir='${libsubdir}/include/c++' ;;
-      *)
-	libstdcxx_incdir=c++/${gcc_version}
-        gxx_include_dir='${prefix}/include/'${libstdcxx_incdir} ;;
-    esac ;;
-  *) gxx_include_dir=${with_gxx_include_dir} ;;
-esac
+TL_AC_GXX_INCLUDE_DIR
 
 FLAGS_FOR_TARGET=
 case " $target_configdirs " in
@@ -2154,8 +2140,6 @@ AC_SUBST(gcc_version)
 AC_SUBST(tooldir)
 AC_SUBST(build_tooldir)
 AC_SUBST(GDB_TK)
-AC_SUBST(gxx_include_dir)
-AC_SUBST(libstdcxx_incdir)
 
 # Build module lists & subconfigure args.
 AC_SUBST(build_configargs)
diff -u /dev/null config/gxx-include-dir.m4
--- /dev/null	Fri Apr 23 00:21:55 2004
+++ config/gxx-include-dir.m4	Thu Nov 25 17:02:22 2004
@@ -0,0 +1,26 @@
+dnl Usage: TL_AC_GXX_INCLUDE_DIR
+dnl
+dnl Set $gxx_include_dir to the location of the installed C++ include
+dnl directory.  The value depends on $gcc_version and the configuration
+dnl options --with-gxx-include-dir and --enable-version-specific-runtime-libs.
+dnl
+dnl If you change the default here, you'll need to change the gcc and
+dnl libstdc++-v3 subdirectories too.
+AC_DEFUN([TL_AC_GXX_INCLUDE_DIR],
+[
+case "${with_gxx_include_dir}" in
+  yes)
+    AC_MSG_ERROR([--with-gxx-include-dir=[[dir]] requires a directory])
+    ;;
+  no | "")
+    case "${enable_version_specific_runtime_libs}" in
+      yes) gxx_include_dir='${libsubdir}/include/c++' ;;
+      *)
+	libstdcxx_incdir=c++/${gcc_version}
+	gxx_include_dir='${prefix}/include/'${libstdcxx_incdir} ;;
+    esac ;;
+  *) gxx_include_dir=${with_gxx_include_dir} ;;
+esac
+AC_SUBST(gxx_include_dir)
+AC_SUBST(libstdcxx_incdir)
+])