main/gcc: upgrade to 12.1.1_git20220630

Limitations:

• GDC has been disabled on all 32-bit architectures due a known upstream bug: https://github.com/dlang/druntime/pull/3383

Changes to alpine-gcc-patches:

• 0038-Fix-attempt-to-use-poisoned-calloc-error-in-libgccji.patch needs to be removed from alpine-gcc-patches
• 0015-dlang-use-libucontext-on-mips64.patch is a nop and should/could also be removed from alpine-gcc-patches

The following patches need to be added to alpine-gcc-patches:

• 0045-druntime-link-against-libucontext-on-all-platforms.patch
• 0046-c-avoid-memory-poisoning-on-musl-PR106102.patch
• 0047-jit-avoid-calloc-poisoning-on-musl-PR106102.patch
• 0053-libgo-make-match.sh-POSIX-shell-compatible.patch
• 0049-libgo-adjust-name-of-union-in-sigevent-struct.patch
• 0050-libphobos-don-t-define-__mode_t-twice-on-musl-target.patch
• 0051-libgo-Explicitly-define-SYS_timer_settime-for-32-bit.patch
• 0052-libgnat-time_t-is-always-64-bit-on-musl-libc.patch