swift234

[ClangImporter] Treat NSUInteger as UInt when it's an enum underlying type.

...rather than Int.

This handles the case where there are existing 32-bit enum constants with
the bit set, which isn't that uncommon for NS_OPTIONS declarations.

Part of <rdar://problem/15368372>, but should also fix the main issue in
<rdar://problem/15236662>.

Swift SVN r14090