examples/resample_audio: check av_samples_get_buffer_size() return code

Fixes CID1135757.
Signed-off-by: Timothy Gu <timothygu99@gmail.com>

doc/examples/resampling_audio.c

@@ -184,6 +184,10 @@ int main(int argc, char **argv)
         }
         dst_bufsize = av_samples_get_buffer_size(&dst_linesize, dst_nb_channels,
                                                  ret, dst_sample_fmt, 1);
+        if (dst_bufsize < 0) {
+            fprintf(stderr, "Could not get sample buffer size\n");
+            goto end;
+        }
         printf("t:%f in:%d out:%d\n", t, src_nb_samples, ret);
         fwrite(dst_data[0], 1, dst_bufsize, dst_file);
     } while (t < 10);