avconv: Check rc_override memory allocation

CC: libav-stable@libav.org
Bug-Id: CID 1265719

avconv_opt.c

@@ -1136,6 +1136,10 @@ static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc)
             video_enc->rc_override =
                 av_realloc(video_enc->rc_override,
                            sizeof(RcOverride) * (i + 1));
+            if (!video_enc->rc_override) {
+                av_log(NULL, AV_LOG_FATAL, "Could not (re)allocate memory for rc_override.\n");
+                exit_program(1);
+            }
             video_enc->rc_override[i].start_frame = start;
             video_enc->rc_override[i].end_frame   = end;
             if (q > 0) {