This translates clang arguments to swift ones, uses the bridging header
functionality to parse the provided file, and re-uses part of the module interface
printing implementation to print an interface for the header.
Part of rdar://19939192
Swift SVN r28062
Brings back the behavior removed in r15800 under a pair of flags
(-module-print-submodules and -module-print-hidden) that control
whether to print submodules, possibly including submodules that aren't
explicitly visible.
Swift SVN r15872
