[swift-evolution] Rewrite imported C function signatures

[Andrey Tarantsov]

Reposting my comment from that other thread:

[...] it's more of an external annotation on C code, something that we don't currently support for user code. (My understanding is that they have it implemented for Apple frameworks.) Perhaps, with Swift 3 going Linux, with should expose the ability to annotate external code to the users? And enum importing could be a part of that.

A.