swift

2e7e33d1 - Ensure that we assign discriminators for closures from top-level macros

Ensure that we assign discriminators for closures from top-level macros In top-level code, we were incorrectly pulling closure discriminators from TopLevelCodeDecls, not from the enclosing source file, which could lead to the same discriminators being assigned to different closures that come from macro expansions at the top level. Hilarity ensures, yet I am not amused. Adjust the DeclContext appropriately when computing discriminators. Fixes rdar://123836908.