lavfi: use av_fifo_freep

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>

libavfilter/buffersink.c

@@ -76,8 +76,7 @@ static av_cold void uninit(AVFilterContext *ctx)
             av_fifo_generic_read(sink->fifo, &frame, sizeof(frame), NULL);
             av_frame_free(&frame);
         }
-        av_fifo_free(sink->fifo);
-        sink->fifo = NULL;
+        av_fifo_freep(&sink->fifo);
     }
 }
 

libavfilter/buffersrc.c

@@ -426,8 +426,7 @@ static av_cold void uninit(AVFilterContext *ctx)
         av_fifo_generic_read(s->fifo, &frame, sizeof(frame), NULL);
         av_frame_free(&frame);
     }
-    av_fifo_free(s->fifo);
-    s->fifo = NULL;
+    av_fifo_freep(&s->fifo);
 }
 
 static int query_formats(AVFilterContext *ctx)

libavfilter/vf_fps.c

@@ -103,7 +103,7 @@ static av_cold void uninit(AVFilterContext *ctx)
     if (s->fifo) {
         s->drop += av_fifo_size(s->fifo) / sizeof(AVFrame*);
         flush_fifo(s->fifo);
-        av_fifo_free(s->fifo);
+        av_fifo_freep(&s->fifo);
     }
 
     av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "