aacdec: Rename avccontext to avctx.

Originally committed as revision 23488 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/aac.h

@@ -241,7 +241,7 @@ typedef struct {
  * main AAC context
  */
 typedef struct {
-    AVCodecContext * avccontext;
+    AVCodecContext * avctx;
 
     MPEG4AudioConfig m4ac;