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 duma_2_5_8.orig/Makefile duma_2_5_8/Makefile

--- duma_2_5_8.orig/Makefile	2007-09-07 21:57:45.000000000 +0200

+++ duma_2_5_8/Makefile	2007-09-07 21:58:35.000000000 +0200

@@ -216,9 +216,13 @@

 	dumatest.c tstheap.c testmt.c dumatestpp.cpp testoperators.cpp \

 	createconf.c

-OBJECTS = dumapp.o duma.o sem_inc.o print.o

+OBJECTS = duma.o sem_inc.o print.o

+SO_OBJECTS = duma_so.o sem_inc_so.o print_so.o

-SO_OBJECTS = dumapp_so.o duma_so.o sem_inc_so.o print_so.o

+ifeq ($(DUMA_CPP),1)

+OBJECTS += dumapp.o

+SO_OBJECTS += dumapp_so.o

+endif

 all:	libduma.a tstheap$(EXEPOSTFIX) dumatest$(EXEPOSTFIX) testmt$(EXEPOSTFIX) dumatestpp$(EXEPOSTFIX) testoperators$(EXEPOSTFIX) $(DUMA_DYN_DEPS)

 	@ $(ECHOLF)