avprobe: Fix memory leak

After init_opts() there needs to be an uninit_opts() call
to free the swscale context and other buffers.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

avprobe.c

@@ -1089,7 +1089,7 @@ int main(int argc, char **argv)
     avio_flush(probe_out);
     av_freep(&probe_out);
     av_freep(&buffer);
-
+    uninit_opts();
     avformat_network_deinit();
 
     return ret;