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 Gentoo.

 -= BEGIN original header =-

 -= END original header =-

 diff -durN uClibc-0.9.30.orig/libc/sysdeps/linux/arm/bits/uClibc_arch_features.h uClibc-0.9.30/libc/sysdeps/linux/arm/bits/uClibc_arch_features.h

 --- uClibc-0.9.30.orig/libc/sysdeps/linux/arm/bits/uClibc_arch_features.h	2008-09-25 10:50:56.000000000 +0200

 +++ uClibc-0.9.30/libc/sysdeps/linux/arm/bits/uClibc_arch_features.h	2009-02-07 09:57:59.000000000 +0100

 @@ -39,4 +39,8 @@

  /* define if target supports IEEE signed zero floats */

  #define __UCLIBC_HAVE_SIGNED_ZERO__

 +#ifdef __ARM_EABI__

 +# define __UCLIBC_TRUNCATE64_HAS_4_ARGS__

 +#endif

 +

  #endif /* _BITS_UCLIBC_ARCH_FEATURES_H */