Same string as the kernel commit, for the three compiled aports this image
builds itself: -march=armv8.6-a+fp16fml+aes+sha3+sm4 -mtune=cortex-a720
appended to CFLAGS (and CXXFLAGS for libcamera). abuild builds these with
Alpine's GCC; the string is gcc's own -march=native expansion on the phone
re-based on armv8.6-a, and it assembles on GCC 15 with binutils 2.45.1 and
on GCC 16 (whose -mcpu=cortex-a720 expansion binutils 2.45 rejects). On the
phone itself gcc -flto, g++ and clang all compile, link and run it.
The base stops at 8.6 on purpose: this phone exposes neither SVE nor MTE
(userspace autovectorised for SVE2 would SIGILL), and not WFxT either.
pkgrel bumps so apk upgrade delivers the rebuilt binaries.