TAPI with LLVM-10

[sbingner]

Not really an “issue” but I have tapi compiling with apple llvm-10 instead of the version it listed in case that is somehow useful for you at https://github.com/sbingner/llvm-project - didn’t see a better place to make you aware of it. Only thing I had to do to llvm was revert one commit, should probably have implemented the function in tapi instead.

The primary advantage here is that it supports arm64e

This also builds the tapi binary in addition to libtapi.