Fix SendText AMI action to never return non-zero.

AMI actions must never return non-zero unless they intend to close the AMI
connection.  (Which is almost never.)

(closes issue ASTERISK-21779)
Reported by: Paul Goldbaum
........

Merged revisions 388477 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@388478 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/manager.c

@@ -3700,7 +3700,7 @@ static int action_sendtext(struct mansession *s, const struct message *m)
 		astman_send_error(s, m, "Failure");
 	}
 
-	return res;
+	return 0;
 }
 
 /*! \brief  action_redirect: The redirect manager command */