swift

ebc0a377 - Set Swift language version to 5

Set Swift language version to 5 The stdlib needs to build in Swift-5 mode, and ensure that `-swift-verion 5` be included in the commandline explicitly. While the compiler defaults to 5 mode, if it's not included explicitly, it won't be included in the swift interface, which then means that modules that import it will influence how the textual interface is processed. The interface for the stdlib must be processed in the Swift 5 language mode due to sendability. Set it explicitly to ensure that importing modules do not change the Swift language mode. Fixes: rdar://145118843