Always build a builtin operator expression for the __extension__ unary operator.

llvm-svn: 88811
diff --git a/clang/test/SemaCXX/overloaded-builtin-operators.cpp b/clang/test/SemaCXX/overloaded-builtin-operators.cpp
index 89ac29a..fd0cbc6 100644
--- a/clang/test/SemaCXX/overloaded-builtin-operators.cpp
+++ b/clang/test/SemaCXX/overloaded-builtin-operators.cpp
@@ -185,3 +185,6 @@
   return a[X][X];
 }
 
+void f() {
+  (void)__extension__(A());
+}