[SystemZ]  Improve handling of instructions which expand to several groups

Some instructions expand to more than one decoder group.

This has been hitherto ignored, but is handled with this patch.

Review: Ulrich Weigand
https://reviews.llvm.org/D50187

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338849 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed