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>

This is the README for crosstool-NG

Crosstool-NG follows the autoconf dance. So, to get you

kick-started, just run:

  ./configure --help

You will find the documentation in the directory 'docs'.

Here is a quick overview of what you'll find there:

  0 - Table of content

  1 - Introduction

  2 - Installing crosstool-NG

  3 - Configuring a toolchain

  4 - Building the toolchain

  5 - Using the toolchain

  6 - Toolchain types

  7 - Contributing

  8 - Internals

  A - Credits

  B - Known issues

  C - Misc. tutorials

You can also point your browser at:

  http://ymorin.is-a-geek.org/projects/crosstool

Aloha!