cc/gcc: add the backend/frontend infra for final gcc

Currently, we issue the bare-metal compiler from the pass_1 & pass_2
core compilers, because the final gcc breaks while doing so.

This implies we have to build some libces during the start_files step,
instead of the standard libc step. This is the case for newlib.

By adding a backend/frontend infra to the final gcc, we can abstract
what backend to call: the standard backend for non-bare-metal gcc,
and the core backend for bare-metal.

This patch is just an no-op, it just adds the final backend and
frontend without changing the way bare-metal is built, to come in a
subsequent patch.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 diff -durN binutils-2.20.1.orig/ld/emulparams/elf_i386.sh binutils-2.20.1/ld/emulparams/elf_i386.sh

 --- binutils-2.20.1.orig/ld/emulparams/elf_i386.sh	2009-07-29 16:59:23.000000000 +0200

 +++ binutils-2.20.1/ld/emulparams/elf_i386.sh	2010-08-17 19:32:12.000000000 +0200

 @@ -13,3 +13,13 @@

  NO_SMALL_DATA=yes

  SEPARATE_GOTPLT=12

  IREL_IN_PLT=

 +

 +# In Gentoo, we install 32bit libs into /lib32 in an

 +# ABI setup with amd64/x86

 +case "$target" in

 +  x86_64*-linux*)

 +    case "$EMULATION_NAME" in

 +      *i386*) LIBPATH_SUFFIX=32  ;;

 +    esac

 +  ;;

 +esac