Add regression test for rdar://problem/108319167

Author: slavapestov

validation-test/compiler_crashers_2_fixed/rdar108319167.swift

@@ -0,0 +1,18 @@
+// RUN: %target-swift-frontend -emit-ir %s
+
+public protocol P {}
+
+public protocol Q {
+  associatedtype A: P
+}
+
+public func f<T: P>(_: T) {}
+
+public func foo1<each T: Q, each U>(t: repeat each T, u: repeat each U)
+    where repeat (each U) == (each T).A {
+  repeat f(each u)
+}
+
+public func foo2<each T: Q>(t: repeat each T, u: repeat each T.A) {
+  repeat f(each u)
+}