Add support for parsing ARM arithmetic instructions that update or don't update

the condition codes.  Where the ones that do have an 's' suffix and the ones
that don't don't have the suffix.  The trick is if MatchInstructionImpl() fails
we try again after adding a CCOut operand with the correct value and removing
the 's' if present.  Four simple test cases added for now, lots more to come.

llvm-svn: 121401