cosmetics: Consistently use C-style comments with multiple inclusion guards

libavfilter/formats.h

@@ -218,4 +218,4 @@ void ff_formats_unref(AVFilterFormats **ref);
  */
 void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref);
 
-#endif // AVFILTER_FORMATS_H
+#endif /* AVFILTER_FORMATS_H */

libavfilter/version.h

@@ -51,4 +51,4 @@
 #define FF_API_FOO_COUNT                    (LIBAVFILTER_VERSION_MAJOR < 4)
 #endif
 
-#endif // AVFILTER_VERSION_H
+#endif /* AVFILTER_VERSION_H */

libavutil/dict.h

@@ -118,4 +118,4 @@ void av_dict_free(AVDictionary **m);
  * @}
  */
 
-#endif // AVUTIL_DICT_H
+#endif /* AVUTIL_DICT_H */