Mark x86 _alt instructions as AsmParserOnly so they will be omitted from disassembler without string matches.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198545 91177308-0d34-0410-b5e6-96231b3b80d8
Remove no longer needed x86 disassembler hack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198546 91177308-0d34-0410-b5e6-96231b3b80d8
Fix encoding for PUSH64i16. Add In64BitMode Predicate. Remove disassembler hack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198547 91177308-0d34-0410-b5e6-96231b3b80d8