libbb: make parse_chown_usergroup_or_die() set unspecified uid/gid to -1

function                                             old     new   delta
parse_chown_usergroup_or_die                         102     115     +13
chown_main                                           190     175     -15
start_stop_daemon_main                              1043    1027     -16
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 13/-31)            Total: -18 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/debianutils/start_stop_daemon.c b/debianutils/start_stop_daemon.c
index 42f1943..d7c730f 100644
--- a/debianutils/start_stop_daemon.c
+++ b/debianutils/start_stop_daemon.c
@@ -539,15 +539,15 @@
 		write_pidfile(pidfile);
 	}
 	if (opt & OPT_c) {
-		struct bb_uidgid_t ugid = { -1, -1 };
+		struct bb_uidgid_t ugid;
 		parse_chown_usergroup_or_die(&ugid, chuid);
-		if (ugid.uid != (uid_t) -1) {
+		if (ugid.uid != (uid_t) -1L) {
 			struct passwd *pw = xgetpwuid(ugid.uid);
-			if (ugid.gid != (gid_t) -1)
+			if (ugid.gid != (gid_t) -1L)
 				pw->pw_gid = ugid.gid;
 			/* initgroups, setgid, setuid: */
 			change_identity(pw);
-		} else if (ugid.gid != (gid_t) -1) {
+		} else if (ugid.gid != (gid_t) -1L) {
 			xsetgid(ugid.gid);
 			setgroups(1, &ugid.gid);
 		}