37476287bf
After updating the minimum required LLVM version to 12 we can use apple-a14 as that is closer in features to the Apple M1 than the A12. Once the minimum required LLVM version is updated to 13 we can use apple-m1.
rustc_target contains some very low-level details that are
specific to different compilation targets and so forth.
For more information about how rustc works, see the rustc dev guide.