[ABI][NFC] Fix the confusion of ByVal and ByRef argument names
The second argument of getNaturalAlignIndirect() was bool ByRef, but
the implementation was just delegating to getIndirect() with ByRef
passed unchanged to bool ByVal parameter of getIndirect().
Fix a couple of /*ByRef=*/ comments as well.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D85113