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 ELFkickers.orig/sstrip/Makefile ELFkickers/sstrip/Makefile

 --- ELFkickers.orig/sstrip/Makefile	2001-03-24 12:58:27.000000000 +0100

 +++ ELFkickers/sstrip/Makefile	2007-05-31 21:17:18.000000000 +0200

 @@ -1,7 +1,7 @@

  #  Makefile for sstrip

  sstrip: sstrip.c

 -	gcc -ggdb -Wall -W -o sstrip sstrip.c

 +	$(CC) -Wall -W -o sstrip sstrip.c

  clean:

  	rm -f sstrip