Serialization: Actually deserialize same-shape requirements

I added a test for this a while ago... but the test wasn't running. Fix the
test, and fix the bug.

Author: slavapestov

lib/Serialization/Deserialization.cpp

@@ -862,6 +862,7 @@ static Optional<RequirementKind> getActualRequirementKind(uint64_t rawKind) {
     return RequirementKind::KIND;
 
   switch (rawKind) {
+  CASE(SameShape)
   CASE(Conformance)
   CASE(Superclass)
   CASE(SameType)

test/Serialization/Inputs/pack_expansion_type_other.swift

@@ -4,8 +4,9 @@ public func variadicFunction<each T, each U>(t: repeat each T, u: repeat each U)
 }
 
 public struct VariadicType<each T> {
+  public init() {}
+
   public func variadicMethod<each U>(t: repeat each T, u: repeat each U) -> (repeat (each T, each U)) {
-    // FIXME: return (repeat (each t, each u))
-    fatalError()
+    return (repeat (each t, each u))
   }
 }

test/Serialization/pack_expansion_type.swift

@@ -1,11 +1,11 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend %S/Inputs/pack_expansion_type_other.swift -emit-module -emit-module-path %t/pack_expansion_type_other.swiftmodule -enable-experimental-feature VariadicGenerics
+// RUN: %target-typecheck-verify-swift -I %t -enable-experimental-feature VariadicGenerics
 
 // Experimental features require an asserts compiler
 // REQUIRES: asserts
 
 import pack_expansion_type_other
 
-variadicFunction(t: 1, 2, u: "hi", "bye")
-
-VariadicType<Int, String>.variadicMethod(t: 1, 2, u: "hi", "bye")
+_ = variadicFunction(t: 1, 2, u: "hi", "bye")
+_ = VariadicType().variadicMethod(t: 1, "hi", u: "bye", 3)