swift234

[ClangImporter] Import anonymous enums as Int rather than CInt.

More precisely, import anonymous enums with no fixed underlying type as Int
if they would have fit in a 32-bit signed integer. If not, we can't be sure
"Int" is a valid type for code that compiles for multiple architectures.

(Currently that means we'll fall back to the C type, which is probably /also/
wrong for multiple architectures. We could try to be smarter here, since we
have the number of required bits, but let's start with just this.)

Also, remove existing code that assumed that any 64-bit underlying type was
compatible with Int, which it definitely isn't any more on 32-bit platforms.

Part of <rdar://problem/15368372>

Swift SVN r14089