AArch64: allow MOV (imm) alias to be printed

The backend has been around for years, it's pretty ridiculous that we can't
even use the preferred form for printing "MOV" aliases. Unfortunately, TableGen
can't handle the complex predicates when printing so it's a bunch of nasty C++.
Oh well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272865 91177308-0d34-0410-b5e6-96231b3b80d8
42 files changed