stage2: Implement `@bitReverse` and `@byteSwap`

This change implements the above built-ins for Sema and the LLVM
backend. Other backends have had placeholders added for lowering.
ef417f19e1Cody Tapscott committed on 2/18/2022, 9:28:32 PMparentdee96e2
17 files changedLine totals unavailable