Pre-commit test: [Clang] Do not warn for serialized builtin or command-line definitions

Author: jmmartinez

clang/test/Preprocessor/macro_reserved.i

@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -x cpp-output %s
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wreserved-macro-identifier"
+# 1 "<built-in>" 1
+#define __BUILTIN__ // expected-warning {{macro name is a reserved identifier}}
+# 2 "<command line>" 1
+#define __CMD__ // expected-warning {{macro name is a reserved identifier}}
+# 3 "biz.cpp" 1
+#define __SOME_FILE__ // expected-warning {{macro name is a reserved identifier}}
+int v;
+#pragma clang diagnostic pop