swift234

[ClangImporter] Hide old API from the Carbon days.

This affects the MacTypes.h header in the Darwin module as well as the
CarbonCore and OSServices sub-frameworks of the CoreServices framework.
API hidden in this way can still be accessed through qualified lookup
in case it's really needed, but will not appear in the module interface
or in code completion.

This is a hack, and it would be nice to remove it if/when all of this API
is officially marked as deprecated. I did check with Nick for MacTypes.h
and Chris Linn from CoreServices that this was a reasonable action to take.

rdar://problem/16806148

Swift SVN r24424