[crashers] Add license headers for crash case #28180

Crash case originally submitted here:
practicalswift/swift-compiler-crashes#96

Apache licensing approval given here:
#1649

Author: practicalswift

validation-test/compiler_crashers/28180-rawrepresentable-extension-with-initializer.swift

@@ -1,3 +1,10 @@
+// This source file is part of the Swift.org open source project
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
 // RUN: not --crash %target-swift-frontend %s -parse
 
 // ASAN Output: stack-overflow on address 0x7fff31bf3ff8 (pc 0x0000022f8f44 bp 0x7fff31bf49d0 sp 0x7fff31bf4000 T0)