Seems like cross compiling works with 16.4.2 but fails with 16.11.1.

Launched a huge batch of builds for every last patch version for each minor in between to pinpoint the last known good version.

Seems like 16.10.0 (libv8 9.3) works, contrary to 16.11.1 (libv8 9.4)

• fails on musl with 2.5 and 2.6 because of missing backtrace_symbols GNUism (but not on 2.7, go figure)
• test fails on musl with 3.0 because of this upstream issue
• this built only a darwin 19 gem although it ran the loop (not that it really matters, they're all the same, so moving to a single versionless gem)
• no musl aarch64 build for now