ObjectiveC migrator: infer NS_ENUM even when user
specified NSUInteger as the followup typedef.
With this change, NS_OPTIONS is only inferred
based on looking up how enumerators are speficied
(if they her hexadecimal, power of 2, or have
 bitwise constant expressions).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189682 91177308-0d34-0410-b5e6-96231b3b80d8