swift234

Add some missing cmake dependencies

The only interesting bit is that for stdlib/objc to build reliably, its
.o files all need to depend on the generated swiftmodule files for any
of its library dependencies.  It looks like cmake treats
target_link_libraries as only implying a dependency between the
resulting libraries, and not the objects.  For now, I've achieved this
by making the objects depend on the whole target (which includes
linking), but only the swiftmodule is actually necessary.

Swift SVN r20240