cc/gcc: comonalise the manuals build decision

Let the final frontend decide whether or not to build the manuals.

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

cc/gcc: do not use the core pass-2 to build the baremetal compiler

In case we build a baremetal compiler, use the standard passes:
- core_cc is used to build the C library;
- as such, it is meant to run on build, not host;
- the final compiler is meant to run on host;

As the current final compiler step can not build a baremetal compiler,
call the core backend from the final step.

NB: Currently, newlib is built during the start_files pass, so we have
to have a core compiler by then... Once we can build the baremetal
compiler from the final cc step, then we can move the newlib build to
the proper step, and then get rid of the core pass-1 static compiler...

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

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>

cc/gcc: add 'cflags' paramater to the core backend

As the core backend is used to generate the bare-metal compiler,
we need to pass it the host CFLAGS.

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

cc/gcc: add host parameter to core compiler build process

Tell the core compiler what host it should run on (instead of
hard-coding runing on CT_HOST).

No functional change so far, switching between CT_HOST and CT_BUILD
will come in a following patch.

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

cc/gcc: pass the install prefix to the core passes

Currently, the discrimination on the core compilers prefixes depends on
the type of core compiler to build.

This is not correct, and the caller of the core backend should specify
the prefix.

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

cc/gcc: pass the companion libs prefix to cc_core

In case of canadian-cross, the companion libraries are not the same for
the core cc (they run on 'build') as they are for the final cc (they run
on 'host').

Prepare for this differentiation (coming later), while retaining the
current behavior (to use the same compblibs).

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

cc/gcc: rename the core backend function

Rename the core backend function to do_cc_core_backend, to
make it explicit it is a backend.

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

cc/gcc: simplify calls to core backend

The core backend is going to have more parameters in the upcoming
patches, so it will be a bit complex to handle.

Introduce an array-variable that is filled by the different code-paths
with the required values.

This makes the code easier to read and maintain.

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

kernel/linux: update to latest versions

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