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>

 --- libc/nptl/sysdeps/unix/sysv/linux/alpha/sysdep-cancel.h    2006/10/29 21:48:06     1.6

 +++ libc/nptl/sysdeps/unix/sysv/linux/alpha/sysdep-cancel.h    2007/03/13 21:28:03     1.7

 @@ -55,6 +55,7 @@

  	bne	a3, SYSCALL_ERROR_LABEL;			\

  __LABEL($pseudo_ret)						\

  	.subsection 2;						\

 +	cfi_startproc;						\

  __LABEL($pseudo_cancel)						\

  	subq	sp, 64, sp;					\

  	cfi_def_cfa_offset(64);					\

 @@ -90,12 +91,13 @@

  	cfi_def_cfa_offset(0);					\

  __LABEL($syscall_error)						\

  	SYSCALL_ERROR_HANDLER;					\

 +	cfi_endproc;						\

  	.previous

  # undef PSEUDO_END

  # define PSEUDO_END(sym)					\

 -	.subsection 2;						\

  	cfi_endproc;						\

 +	.subsection 2;						\

  	.size sym, .-sym

  # define SAVE_ARGS_0	/* Nothing.  */