Introduce inferred framework modules into the module map file,

allowing a module map to be placed one level above the '.framework'
directories to specify that all .frameworks within that directory can
be inferred as framework modules. One can also specifically exclude
frameworks known not to work.

This makes explicit (and more restricted) behavior modules have had
"forever", where *any* .framework was assumed to be able to be built
as a module. That's not necessarily true, so we white-list directories
(with exclusions) when those directories have been audited.

llvm-svn: 167482