Remove explicit filename from Doxygen @file commands.

Passing an explicit filename to this command is only necessary if the
documentation in the @file block refers to a file different from the
one the block resides in.

Originally committed as revision 22921 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/options.c

@@ -21,7 +21,7 @@
 #include "libavcodec/opt.h"
 
 /**
- * @file libavformat/options.c
+ * @file
  * Options definition for AVFormatContext.
  */