swift

500d2e58 - [Dependency Scanning] Only omit Clang VFS overlays from Swift dependencies if unused by Clang dependencies

[Dependency Scanning] Only omit Clang VFS overlays from Swift dependencies if unused by Clang dependencies We previously blanket omitted `-Xcc -vfsoverlay` flags from Swift module dependencies' command-line recipes. This is incorrect as the Swift module must have an exact matching VFS overlay that its Clang dependencies use, in order to load said Clang dependnecies successfully and resolve their headers as expected and as was done during the scan. Resolves rdar://122667530