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>

 2007-03-13  Mike Frysinger  <vapier@gentoo.org>

 	* sysdeps/unix/sysv/linux/sh/sys/procfs.h: Copy Linux's asm-sh/elf.h types.

 --- glibc-2_9/sysdeps/unix/sysv/linux/sh/sys/procfs.h

 +++ glibc-2_9/sysdeps/unix/sysv/linux/sh/sys/procfs.h

 @@ -29,10 +29,19 @@

  #include <sys/types.h>

  #include <sys/ucontext.h>

  #include <sys/user.h>

 -#include <asm/elf.h>

  __BEGIN_DECLS

 +/*

 + * ELF register definitions...

 + */

 +typedef unsigned long elf_greg_t;

 +

 +#define ELF_NGREG (sizeof (struct pt_regs) / sizeof(elf_greg_t))

 +typedef elf_greg_t elf_gregset_t[ELF_NGREG];

 +

 +typedef struct user_fpu_struct elf_fpregset_t;

 +

  struct elf_siginfo

    {

      int si_signo;			/* Signal number.  */