Add __FILE_NAME__ to ReleaseNotes. NFC
Add __FILE_NAME__ to ReleaseNotes. NFC

Added it under C language changes as a nonstandard
extension for the time being.



git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@362581 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang