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>

#!@@CT_bash@@

# What we need:

#  - the .config file

# Parse the tools' paths configuration

. "${CT_LIB_DIR}/paths.sh"

# We'll need the stdout later, save it

exec 7>&1

# Parse the common functions

. "${CT_LIB_DIR}/scripts/functions"

# Don't care about any log file

exec >/dev/null

rm -f "${tmp_log_file}"

# Parse the configuration file

. .config.2

# Parse architecture and kernel specific functions

. "${CT_LIB_DIR}/scripts/build/arch/${CT_ARCH}.sh"

. "${CT_LIB_DIR}/scripts/build/kernel/${CT_KERNEL}.sh"

# Build CT_TARGET

CT_DoBuildTargetTuple

# All this for this single echo... :-( Sigh, I'll have to re-arrange things...

echo "${CT_TARGET}" >&7