avcodec: fix pointer aliasing

av_freep() requires a pointer to void *. Nothing else is defined.

modules/codec/avcodec/avcodec.c

@@ -341,7 +341,7 @@ static void CloseDecoder( vlc_object_t *p_this )
 
     decoder_sys_t *p_sys = p_dec->p_sys;
 
-    av_freep( &p_sys->p_context->extradata );
+    av_free( p_sys->p_context->extradata );
     avcodec_free_context( &p_sys->p_context );
     free( p_sys );
 }

modules/codec/avcodec/encoder.c

@@ -1408,7 +1408,8 @@ void CloseEncoder( vlc_object_t *p_this )
 #if (LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(54, 28, 0))
     avcodec_free_frame( &p_sys->frame );
 #else
-    av_freep( &p_sys->frame );
+    av_free( p_sys->frame );
+    p_sys->frame = NULL;
 #endif
 
     vlc_avcodec_lock();