Fixed warning in astman for gcc-4.8.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395984 65c4cc65-6c06-0410-ace0-fbb531ad65f3

utils/astman.c

@@ -737,7 +737,7 @@ static int manager_login(char *hostname)
 					show_message("Login Failed", get_header(m, "Message"));
 				}
 			} else {
-				memset(m, 0, sizeof(m));
+				memset(m, 0, sizeof(*m));
 				manager_action("Login", 
 					"Username: %s\r\n"
 					"Secret: %s\r\n",