Change ppapi C++ comment style into C.

ppapi/c/pp_stdint.h

Index: ppapi/c/pp_stdint.h
diff --git a/ppapi/c/pp_stdint.h b/ppapi/c/pp_stdint.h
index 23a7b7889173d7240539a85c48f7ea38b0ee9c87..2875e4b4ac1b4f5849b7f5ef2403f10044aa449b 100644
--- a/ppapi/c/pp_stdint.h
+++ b/ppapi/c/pp_stdint.h
@@ -1,7 +1,7 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
+/* Copyright (c) 2010 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
 #ifndef PPAPI_C_PP_STDINT_H_
 #define PPAPI_C_PP_STDINT_H_
 
@@ -28,10 +28,11 @@ typedef unsigned __int64 uint64_t;
 #include <stdint.h>
 #endif
 
-#include <stddef.h>  // Needed for size_t.
+#include <stddef.h>  /* Needed for size_t. */
 
 /**
  * @}
  * End addtogroup PP
  */
-#endif  // PPAPI_C_PP_STDINT_H_
+#endif  /* PPAPI_C_PP_STDINT_H_ */
+