CLEANUP: connection: conn->xprt is never NULL

Let's remove this outdated test that's been there since 1.5. For quite
some time now xprt hasn't been NULL anymore on an initialized connection.
diff --git a/src/connection.c b/src/connection.c
index 320a387..6c8855f 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -71,7 +71,7 @@
 	    conn->xprt_done_cb && conn->xprt_done_cb(conn) < 0)
 		return;
 
-	if (conn->xprt && fd_send_ready(fd) && fd_send_active(fd)) {
+	if (fd_send_ready(fd) && fd_send_active(fd)) {
 		/* force reporting of activity by clearing the previous flags :
 		 * we'll have at least ERROR or CONNECTED at the end of an I/O,
 		 * both of which will be detected below.
@@ -99,7 +99,7 @@
 	 * that we must absolutely test conn->xprt at each step in case it suddenly
 	 * changes due to a quick unexpected close().
 	 */
-	if (conn->xprt && fd_recv_ready(fd) && fd_recv_active(fd)) {
+	if (fd_recv_ready(fd) && fd_recv_active(fd)) {
 		/* force reporting of activity by clearing the previous flags :
 		 * we'll have at least ERROR or CONNECTED at the end of an I/O,
 		 * both of which will be detected below.