Add JIT support on Darwin arm64 #89
Description
Since a24dc07, we have disabled building the JIT by default on macOS on M1 (implemented in our case as Darwin on arm64) since GNU Lightning 2.1.3 gets stuck on those machines.
Resolving this issue really just requires GNU Lightning to be patched to work on Macs with M1 chips. Until that happens (or until we switch JIT engines again as we did in #32), this issue is blocked. Sticking with GNU Lightning seems like the best plan for now, though.