Use full internal pathname in doxygen @file directives.

Otherwise doxygen complains about ambiguous filenames when files exist
under the same name in different subdirectories.


git-svn-id: file:///var/local/repositories/mplayer/trunk/libswscale@28414 b3059339-0415-0410-9bf9-f77b7e298cf2

swscale.h

@@ -22,7 +22,7 @@
 #define SWSCALE_SWSCALE_H
 
 /**
- * @file swscale.h
+ * @file libswscale/swscale.h
  * @brief
  *     external api for the swscale stuff
  */