Switch to the new MingW ABI.

GCC 4.7 changed the MingW ABI. On the clang side this means that methods now
have the thiscall calling convention by default.

llvm-svn: 197164
diff --git a/clang/test/CodeGenCXX/copy-assign-synthesis-2.cpp b/clang/test/CodeGenCXX/copy-assign-synthesis-2.cpp
index 18e92f9..3829f38 100644
--- a/clang/test/CodeGenCXX/copy-assign-synthesis-2.cpp
+++ b/clang/test/CodeGenCXX/copy-assign-synthesis-2.cpp
@@ -1,4 +1,4 @@
 // RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
 struct A {};
 A& (A::*x)(const A&) = &A::operator=;
-// CHECK-LABEL: define linkonce_odr %struct.A* @_ZN1AaSERKS_
+// CHECK-LABEL: define linkonce_odr {{.*}}%struct.A* @_ZN1AaSERKS_