[SystemZ] Use RISBG for (shift (and ...))

Another patch in the series to make more use of R.SBG.  This one extends
r186072 and r186073 to handle cases where the AND is inside the shift.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186399 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Add MC support for R[NOX]SBG

CodeGen support will come later.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186401 91177308-0d34-0410-b5e6-96231b3b80d8
Fixing a buildbot failure:unused function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186403 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Use ROSBG and non-zero form of RISBG for OR nodes


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186405 91177308-0d34-0410-b5e6-96231b3b80d8