[ARMv8] Add some missing tests for DSB/DMB.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190060 91177308-0d34-0410-b5e6-96231b3b80d8
Reformat.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190064 91177308-0d34-0410-b5e6-96231b3b80d8
Rename enums to match convention and remove superfluous "dwarf" in names.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190067 91177308-0d34-0410-b5e6-96231b3b80d8