Refactor and reduce code duplication for non-split dwarf strings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198233 91177308-0d34-0410-b5e6-96231b3b80d8
ARM IAS: account for predicated pre-UAL mnemonics

Checking the trailing letter of the mnemonic is insufficient.  Be more thorough
in the scanning of the instruction to ensure that we correctly work with the
predicated mnemonics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198235 91177308-0d34-0410-b5e6-96231b3b80d8