ARCH_FLAGS was always present and is documented as being fed to both
CC and LD during the build. This is meant for options that need to be
consistent between the two stages such as -pg, -flto, -fsanitize=address,
-m64, -g etc. Its doc was lacking a bit of clarity though, and it was
not enumerated in the makefile's variables list.
ARCH however was only documented as affecting ARCH_FLAGS, and was just
never used as the only two really usable and supported ARCH_FLAGS options
were -m32 and -m64. In addition it was even written in the makefile that
it was CPU that was affecting the ARCH_FLAGS. Let's just drop ARCH and
improve the documentation on ARCH_FLAGS. Again, if ARCH is set, a warning
is emitted explaining how to proceed.
ARCH_FLAGS is now preset to -g so that we finally have a correct place
to deal with such debugging options that need to be passed to both
stages. The fedora and musl CI workflows were updated to also use it
instead of sticking to duplicate DEBUG_CFLAGS+LDFLAGS.
It's also worth noting that BUILD_ARCH was being passed to the build
process and never used anywhere in the code, so its removal will not
be noticed.
tracking bleeding edge changes with some rare platforms or modern
compilers on scheduled basis is not what usually forks do. let's
skip by default in forks, if some fork is interested, it might be
enabled locally
Fedora Rawhide is shipped with the most recent compilers, not yet released with
more conservative distro. It is good to catch compile errors on those compilers.
