[ASTReader] Add test for previous change r306583 / 145692e.

Summary:
Add a test for the change to ASTReader that reproduces the
logic for consolidating multiple ObjC interface definitions to the
case of multiple ObjC protocol definitions.

This test is a modified copy of the test that accompanied the original
change to interfaces, in 2ba1979.

Reviewers: bruno

Reviewed By: bruno

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D34788

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306732 91177308-0d34-0410-b5e6-96231b3b80d8

test/Modules/Inputs/lookup-assert-protocol/Base.h

@@ -0,0 +1,3 @@
+@protocol BaseProtocol
+- (void) test;
+@end

test/Modules/Inputs/lookup-assert-protocol/Derive.h

@@ -0,0 +1,4 @@
+#include "Base.h"
+@protocol DerivedProtocol<BaseProtocol>
+- (void) test2;
+@end

test/Modules/Inputs/lookup-assert-protocol/H3.h

@@ -0,0 +1 @@
+#include "Base.h"

test/Modules/Inputs/lookup-assert-protocol/module.map

@@ -0,0 +1,4 @@
+module X {
+  header "H3.h"
+  export *
+}

test/Modules/lookup-assert-protocol.m

@@ -0,0 +1,17 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -I %S/Inputs/lookup-assert-protocol %s -verify
+// expected-no-diagnostics
+
+#include "Derive.h"
+#import <H3.h>
+
+__attribute__((objc_root_class))
+@interface Thing<DerivedProtocol>
+@end
+
+@implementation Thing
+- (void)test {
+}
+- (void)test2 {
+}
+@end