`wasmtime` isn't used on `aarch64-apple-darwin`

[tomaka]

wasmtime is disabled on aarch64 other than Linux, because it's not a tier 1 & 2 wasmtime-supported platform.

This makes the full node rather slow.

Maybe we could enable wasmtime for these targets anyway?

[Zombieliu]

yep

[tomaka]

Something noteworthy is that, since wasmtime is enabled for aarch64-linux, it is possible to compile a aarch64 Docker image (with wasmtime enabled) and run it on MacOS.

cc #1548