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>

Original patch from: ../crosstool-NG/ct-ng.trunk/patches/binutils/2.19/160-use-new-ld-dtags.patch

-= BEGIN original header =-

Original patch from Gentoo:

gentoo/src/patchsets/binutils/2.19/76_all_use-new-ld-dtags.patch

-= END original header =-

diff -durN binutils-2.19.1.orig/ld/ldmain.c binutils-2.19.1/ld/ldmain.c

--- binutils-2.19.1.orig/ld/ldmain.c	2009-03-08 11:57:03.000000000 +0100

+++ binutils-2.19.1/ld/ldmain.c	2009-03-08 11:57:03.000000000 +0100

@@ -262,6 +262,7 @@

   link_info.allow_undefined_version = TRUE;

   link_info.keep_memory = TRUE;

+  link_info.new_dtags = TRUE;

   link_info.combreloc = TRUE;

   link_info.strip_discarded = TRUE;

   link_info.emit_hash = TRUE;