swift234

Implement: <rdar://problem/17464179> Stop importing decls with CInt and related typedefs

This keeps CInt (and related type aliases) in the stdlib, and keeps the clang importer
using them, but has it look through one level of the type alias to get to the underlying
type. 

The upshot of this is that we now import things like exit (as a random example) as 
"func exit(Int32)" instead of "func exit(CInt)".



Swift SVN r19224