avfilter/avfiltergraph: return value of ff_request_frame() is unused

Fixes: CID1397741 Unchecked return value

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavfilter/avfiltergraph.c

@@ -1410,7 +1410,7 @@ int avfilter_graph_request_oldest(AVFilterGraph *graph)
         if (r == AVERROR(EAGAIN) &&
             !oldest->frame_wanted_out && !oldesti->frame_blocked_in &&
             !oldesti->status_in)
-            ff_request_frame(oldest);
+            (void)ff_request_frame(oldest);
         else if (r < 0)
             return r;
     }