Add support for the PS4 OS. Update the standard library and add a target unit test.
Add Android to the OS checks used to determine whether to import Glibc. These tests would pass on Android were it not for the fact that Android is not included in the Glibc check. Also add FreeBSD where missing.
StdlibUnittest.swift became StdlibUnittest/Common.swift; all others just dropped the "StdlibUnittest" prefix.