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>

 --- gcc-4.1.2.orig/libstdc++-v3/include/ext/rope	2005-08-17 04:28:44.000000000 +0200

 +++ gcc-4.1.2/libstdc++-v3/include/ext/rope	2007-03-04 23:34:08.000000000 +0100

 @@ -57,6 +57,9 @@

  #include <bits/allocator.h>

  #include <ext/hash_fun.h>

 +/* cope w/ index defined as macro, SuSv3 proposal */

 +#undef index

 +

  # ifdef __GC

  #   define __GC_CONST const

  # else

 --- gcc-4.1.2.orig/libstdc++-v3/include/ext/ropeimpl.h	2005-08-17 04:28:44.000000000 +0200

 +++ gcc-4.1.2/libstdc++-v3/include/ext/ropeimpl.h	2007-03-04 23:34:08.000000000 +0100

 @@ -53,6 +53,9 @@

  #include <ext/memory> // For uninitialized_copy_n

  #include <ext/numeric> // For power

 +/* cope w/ index defined as macro, SuSv3 proposal */

 +#undef index

 +

  namespace __gnu_cxx

  {

    using std::size_t;