swift

4262b7e4 - [Platform] Update musl modulemap and improve musl platform support.

[Platform] Update musl modulemap and improve musl platform support. We need to declare separate top-level modules for every header in the musl C library. Note that our set-up here does require some tweaks to musl itself (specifically, the `alltypes.h` header needs some fairly serious massaging to make it module compatible; in particular, we need to pull out every type declaration into its own separate modularized header in `bits/types`). Also update `Platform.swift` a little for more musl support. rdar://123503615