Use shared_ptr instead of IntrusiveRefCntPtr for ModuleFileExtension

The intrusiveness wasn't needed here, so this simplifies/clarifies the
ownership model.

llvm-svn: 291150
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index ca4a765..86d58a2 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1214,8 +1214,8 @@
 
     // Add the testing module file extension.
     Opts.ModuleFileExtensions.push_back(
-      new TestModuleFileExtension(BlockName, MajorVersion, MinorVersion,
-                                  Hashed, UserInfo));
+        std::make_shared<TestModuleFileExtension>(
+            BlockName, MajorVersion, MinorVersion, Hashed, UserInfo));
   }
 
   if (const Arg *A = Args.getLastArg(OPT_code_completion_at)) {