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>

 Patch from upstream:

 http://strace.cvs.sourceforge.net/viewvc/strace/strace/linux/arm/syscallent.h?r1=1.17&r2=1.18&sortby=file

 2008-11-13  Kirill A. Shutemov  <kirill@shutemov.name>

     * linux/arm/syscallent.h: Fix build on ARM EABI which does not

     provide syscalls socketcall and ipc.

 --- strace-4.5.18.orig/linux/arm/syscallent.h	2008/12/29 20:04:15	1.17

 +++ strace-4.5.18/linux/arm/syscallent.h	2009/01/01 23:20:38	1.18

 @@ -431,6 +431,7 @@

  	{ 5,	0,	printargs,		"SYS_398"	}, /* 398 */

  	{ 5,	0,	printargs,		"SYS_399"	}, /* 399 */

 +#ifndef __ARM_EABI__

  #if SYS_socket_subcall != 400

   #error fix me

  #endif

 @@ -481,3 +482,4 @@

  	{ 4,	TI,	sys_shmdt,		"shmdt"		}, /* 440 */

  	{ 4,	TI,	sys_shmget,		"shmget"	}, /* 441 */

  	{ 4,	TI,	sys_shmctl,		"shmctl"	}, /* 442 */

 +#endif