[SystemZ] Add support for additional branch extended mnemonics

Added support for extended mnemonics for the following branch instructions and
load/store-on-condition opcodes:

BR, LOCR, LOCGR, LOC, LOCG, STOC, STOCG

Phabricator: http://reviews.llvm.org/D19729

Committing on behalf of Zhan Liau

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269106 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed