We call this "zig-build" instead of just "zig" as this build-style
relies on usage of the zig build system. In the future, other build
systems such as meson may support zig code. Furthermore, the zig
build system may be used to build C/C++ code as well, not just zig.
we don't need to specify -mcpu where compiler default is used,
preserve mtune though; do not -mno-altivec on ppc since altivec
is not default in the first place and doing this will just
break random things that explicitly enable altivec for runtime
checked code; do not use -maltivec on either ppc64le or ppc64
since it's implied by their -mcpu's (power8 for ppc64le which
is implicit, and 970 for ppc64 which is explicit)
also remove -mlong-double-64 for musl targets as that's compiler
default and it's not necessary to pass it; also remove -mabi=elfv2
for both ppc64le and ppc64 since it's implied default
Provide new environment variables for simplifaction of template checks:
...ENDIAN defines the (target) machine's endianness: "le" or "be".
...LIBC defines the (target) machine's C library: "glibc" or "musl".
Closes: #13356
Signed-off-by: Jürgen Buchmüller <pullmoll@t-online.de>
