rtmpproto: Check for the right return code

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rtmpproto.c

@@ -2531,7 +2531,7 @@ reconnect:
 
     do {
         ret = get_packet(s, 1);
-    } while (ret == EAGAIN);
+    } while (ret == AVERROR(EAGAIN));
     if (ret < 0)
         goto fail;