swift234

Load Swift modules from framework bundles.

Swift can now find modules inside framework bundles matching this layout:

Foo.framework/
  Foo.swiftmodule/
    ARCH.swiftmodule

Currently, ARCH is the architecture name used by build configurations (#if),
but this was more done out of convenience than anything else (there's
currently no access to the current target from the ASTContext). We'll need
to revisit this if/when we decide to support architecture subtypes (armv7s
vs. armv7 vs. arm), at which point we'll also have to deal with fallback
architectures.

Framework search paths are specified using -F. Like bare import paths, there
are currently no "built-in framework search paths".

The master plan for Swift frameworks is in <rdar://problem/16062602>.

<rdar://problem/16155907>

Swift SVN r14363