Merge pull request #3217 from practicalswift/swiftc-28332-swift-archetypebuilder-getgenericsignature

[swiftc] Add 💥 case (😢 → 51, 😀 → 5091) triggered in swift::ArchetypeBuilder::getGenericSignature(…)

Author: slavapestov

validation-test/compiler_crashers/28332-swift-archetypebuilder-getgenericsignature.swift

@@ -0,0 +1,23 @@
+// 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
+// REQUIRES: asserts
+class A{var b=a
+struct Q<h{
+enum a<T{
+extension{
+{{
+}}
+protocol c:a{
+extension{
+{
+}
+protocol A{
+func<
+typealias e:
+Q