ObjectiveC migrator: Infer NS_OPTIONS when if there is at
least one hex enumerator, all others are also
hex enumerator (0 enumerator is excepted). 
// rdar://15044304


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191222 91177308-0d34-0410-b5e6-96231b3b80d8