swift234

SILGen: Emit derived '==' operators from Clang modules with shared linkage.

In Sema, give derived '==' definitions the module's DerivedFileUnit as their decl context instead of the more general Module, and give it a backreference to the nominal type for which it was derived. 
In SILGen, visit the derived global decls associated with Clang-imported enums, and give them shared linkage. Part of fixing <rdar://problem/16264703>.

Swift SVN r14875