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>

YEM-20070519:

Patch from Bernhard Fischer <rep.dot.nop@gmail.com> on the uClibc mailing

list ( http://www.uclibc.org/lists/uclibc/2008-January/018940.html ) above

the 400-bits_sysnum_h.patch.

Index: uClibc/Makefile.in

===================================================================

--- uClibc/Makefile.in	(revision 18651)

+++ uClibc/Makefile.in	(working copy)

@@ -114,7 +116,7 @@ install: install_runtime install_dev

 RUNTIME_PREFIX_LIB_FROM_DEVEL_PREFIX_LIB=$(shell $(top_srcdir)extra/scripts/relative_path.sh $(DEVEL_PREFIX)lib $(RUNTIME_PREFIX)lib)

 # Installs header files.

-install_headers:

+install_headers: headers

 	$(INSTALL) -d $(PREFIX)$(DEVEL_PREFIX)include

 	printf ".svn\n.cvsignore\nCVS\n" > tar_exclude ; \

 	$(TAR) -chf - -X tar_exclude include \