We only record these dependencies in CAS mode, because we require explicit PCH tasks to be produced for imported header of binary module dependencies. In the meantime, in non-CAS mode loading clients will consume the `.h` files encoded in the `.swiftmodules` directly.
Followup changes to SwiftDriver will enable explicit PCH compilation of such dependenceis, but for the time being restore prior behavior for non-CAS explicit module builds.
Resolves rdar://116006619
75ee48ca77