swift234

PrintAsObjC: Detect apps by the presence of a file with a main entry point.

PrintAsObjC behaves slightly differently in apps vs. frameworks: for apps,
you get internal decls exposed in the header as well as public ones. This
is because the generated header is not being shipped anywhere and thus we
don't have a secrecy leak.

However, we were detecting whether we were in an app based on whether or
not we had a bridging header. That's no good for mixed-source apps where
there's no bridging header, so now we also check for a main entry point,
whether generated from @UIApplicationMain or @NSApplicationMain, or from
a script source file (main.swift).

rdar://problem/17877235

Swift SVN r24532