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 -ru ltrace-0.5.3.orig/sysdeps/linux-gnu/Makefile ltrace-0.5.3/sysdeps/linux-gnu/Makefile

--- ltrace-0.5.3.orig/sysdeps/linux-gnu/Makefile	2009-07-25 17:13:02.000000000 +0200

+++ ltrace-0.5.3/sysdeps/linux-gnu/Makefile	2010-01-01 22:20:45.000000000 +0100

@@ -2,6 +2,7 @@

 				-e s/i.86/i386/ \

 				-e s/sun4u/sparc64/ \

 				-e s/sparc64/sparc/ \

+				-e s/alpha.*/alpha/ \

 				-e s/arm.*/arm/ \

 				-e s/sa110/arm/ \

 				-e s/ppc64/ppc/ \