cc/gcc: disable complibs if not selected

Force gcc to not link with some companion libraries when
there are not needed (because selected-out).

There is no option to tell gcc *not* to build the Graphite and/or
LTO stuff. They *will* be built if gcc finds the suitable companion
libraries. If we do not provide them, but the host has them, then
gcc *will* find them, and link with them.

Consider the following:
- host has suitable PPL and CLooG (eg. Debian Squeeze)
- user wants to build gcc>=4.4
- user de-selects GRAPHITE
- gcc will find the hosts PPL and CLooG, and will use them
- the user moves the toolchain to an older host that does
not have them (eg. Debian Lenny)
- the toolchain fails, when it was properly setup not to

So, explicitly tell gcc *not* to use unneeded companion libs.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

diff -dur binutils-2.17.old/ld/emultempl/elf32.em binutils-2.17/ld/emultempl/elf32.em

--- binutils-2.17.old/ld/emultempl/elf32.em	2006-06-12 15:05:04.000000000 +0200

+++ binutils-2.17/ld/emultempl/elf32.em	2007-05-01 18:26:13.000000000 +0200

@@ -970,6 +970,8 @@

 	      && command_line.rpath == NULL)

 	    {

 	      lib_path = (const char *) getenv ("LD_RUN_PATH");

+	      if ((lib_path) && (strlen (lib_path) == 0))

+		  lib_path = NULL;

 	      if (gld${EMULATION_NAME}_search_needed (lib_path, &n,

 						      force))

 		break;

@@ -1154,6 +1156,8 @@

   rpath = command_line.rpath;

   if (rpath == NULL)

     rpath = (const char *) getenv ("LD_RUN_PATH");

+  if ((rpath) && (strlen (rpath) == 0))

+      rpath = NULL;

   if (! (bfd_elf_size_dynamic_sections

 	 (output_bfd, command_line.soname, rpath,

 	  command_line.filter_shlib,