fix variable name for IPv6 case in construct_utmpx

patch from writeonce AT midipix.org via bz#2296

loginrec.c

@@ -787,12 +787,12 @@ construct_utmpx(struct logininfo *li, struct utmpx *utx)
 	/* this is just a 128-bit IPv6 address */
 	if (li->hostaddr.sa.sa_family == AF_INET6) {
 		sa6 = ((struct sockaddr_in6 *)&li->hostaddr.sa);
-		memcpy(ut->ut_addr_v6, sa6->sin6_addr.s6_addr, 16);
+		memcpy(utx->ut_addr_v6, sa6->sin6_addr.s6_addr, 16);
 		if (IN6_IS_ADDR_V4MAPPED(&sa6->sin6_addr)) {
-			ut->ut_addr_v6[0] = ut->ut_addr_v6[3];
-			ut->ut_addr_v6[1] = 0;
-			ut->ut_addr_v6[2] = 0;
-			ut->ut_addr_v6[3] = 0;
+			utx->ut_addr_v6[0] = utx->ut_addr_v6[3];
+			utx->ut_addr_v6[1] = 0;
+			utx->ut_addr_v6[2] = 0;
+			utx->ut_addr_v6[3] = 0;
 		}
 	}
 # endif