g723_1_demuxer: rco is also a commonly used extension.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/g723_1.c

@@ -78,6 +78,6 @@ AVInputFormat ff_g723_1_demuxer = {
     NULL,
     g723_1_init,
     g723_1_read_packet,
-    .extensions = "tco",
+    .extensions = "tco,rco",
     .flags = AVFMT_GENERIC_INDEX
 };