[SystemZ] Immediate compare-and-branch support

This patch adds support for the CIJ and CGIJ instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182846 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Two tests missing from previous commit


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182847 91177308-0d34-0410-b5e6-96231b3b80d8