[AArch64] Support building on GCB
Implemented using buildx to emulate aarch64 using QEMU Related: #8164
Took me all day go from early POC to a version that builds alongside everything else and does bad build check: https://pantheon.corp.google.com/cloud-build/builds;region=us-central1/d16321e9-7e5c-4a80-a681-e34c85f59dbf?project=oss-fuzz
/gcbrun trial_build.py skcms --sanitizer address memory coverage undefined --fuzzing-engine libfuzzer afl honggfuzz --architectures i386 x86_64 aarch64
PTAL
infra-test failure is known and is a straightforward fix to the test that I will do tomorrow
Are we missing a push here? :)
Failures are unrelated.