ARM: move ARMUnwindOp.h into Support

Move the ARM EHABI unwind opcode definitions from the ARM MCTargetDesc into LLVM
Support.  This enables sharing of the definitions across the ARM target code as
well as llvm-readobj.  This will allow implementation of the unwind decoding in
llvm-readobj.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198576 91177308-0d34-0410-b5e6-96231b3b80d8
Try to fix s390x build bot.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198577 91177308-0d34-0410-b5e6-96231b3b80d8
Remove a failing test to get the buildbots back to green.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198578 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor function that checks that __builtin_returnaddress's argument is constant.

This moves the check up into the parent class so that all targets can use it
without having to copy (and keep in sync) the same error message.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198579 91177308-0d34-0410-b5e6-96231b3b80d8