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>

 --- glibc-2.7/sysdeps/unix/sysv/linux/sh/sysdep.S.orig	2005-12-30 22:16:43.000000000 +0000

 +++ glibc-2.7/sysdeps/unix/sysv/linux/sh/sysdep.S	2008-08-19 22:33:14.000000000 +0100

 @@ -32,3 +32,13 @@

  #define __syscall_error __syscall_error_1

  #include <sysdeps/unix/sh/sysdep.S>

 +

 +	.data

 +	.align 3

 +	.globl ___fpscr_values

 +	.type ___fpscr_values, @object

 +	.size ___fpscr_values, 8

 +___fpscr_values:

 +	.long	0

 +	.long	0x80000

 +weak_alias (___fpscr_values, __fpscr_values)

 --- glibc-2.7/sysdeps/unix/sysv/linux/sh/Versions.orig	2003-09-01 05:05:09.000000000 +0100

 +++ glibc-2.7/sysdeps/unix/sysv/linux/sh/Versions	2008-08-19 22:33:14.000000000 +0100

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

    GLIBC_2.2 {

      # functions used in other libraries

      __xstat64; __fxstat64; __lxstat64;

 +    __fpscr_values;

      # a*

      alphasort64;