cc/gcc: pass the language list to the core backend

As the core backend can be used to also build the bare-metal compiler,
we have to tel it what languages to build.

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

cc/gcc: add language helper function

Add a function that prepares the language configure option.
It is needed in at least two places, some commonalisation is needed. ;-)

Unfortunately, it is no longer possible to print warnings about experimental
languages any more. Anyway, the experimental status is clearly indicated
in the menuconfig. so it should not be a surprise if the build breaks. :-/

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

complibs: fixup the host complibs install dir

It's easier to have as much as possible stuff in the same place to
ease backup/restore, and make things easier to follow.

Move the host companion libraries install dir as a sub-dir of the
build-tools install dir (but not directly in it, it would break
for canadian or cross-native).

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

cc/gcc: cleanup the frontends

A few noop fix-ups:
- fix the comments in core pass-1
- commonalise settings that can be

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

complibs: add frontends for building to run on the build machine

In canadian-cross, we need the companion libraries running on the
build machine, to be able to build the two core gcc.

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

binutils: add frontends for building to run on the build machine

In canadian-cross, we need binutils running on the build machine to be
able to build the target C library.

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

complibs: split companion libraries to backend/frontend, a-la cc_core

Move the actual complibs codes to backend functions that builds the
required combo of build/host/target as requested by a frontend.

This split is currently a no-op, but is required for the upcoming
canadian-cross rework, where we'll be needing to build the complibs
twice, one for build/build, and one for build/host.

This applies to the six companion libraries:
- GMP
- MPFR
- PPL
- Cloog/PPL
- MPC
- libelf

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

binutils: split binutils to backend/frontend, a-la cc_core

Move the actual binutils code to a backend function that builds the
required combo of build/host/target as requested by a frontend.

This split is currently a no-op, but is required for the upcoming
canadian-cross rework, where we'll be needing to build two binutils,
one for build/build/target, and one for build/host/target.

This applies to the three binutils:
- GNU binutils
- elf2flt
- sstrip

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

cc/gcc: always build core compilers to run on the build machine

The core compilers are used to build the C library, so they
should always run on the build machine, not on the host.

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

cc/gcc: install the core compilers in the build-tools dir

There really is no good reason to install the core compilers in their
own places, one for each pass. We can install them with the other
build tools.

Also, this implies that:
- there are fewer directories to save/restore
- there are fewer symlinks to create for binutils
- the PATH is shorter

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