Print the address of the AVCodecContext in av_log().

This makes debug output much easier to read when the
same codec is open more than once.

Originally committed as revision 14237 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/log.c

@@ -36,7 +36,7 @@ void av_log_default_callback(void* ptr, int level, const char* fmt, va_list vl)
         return;
 #undef fprintf
     if(print_prefix && avc) {
-            fprintf(stderr, "[%s @ %p]", avc->item_name(ptr), avc);
+            fprintf(stderr, "[%s @ %p]", avc->item_name(ptr), ptr);
     }
 #define fprintf please_use_av_log