utmpx.h: add ut_host for compatibility (not posix)

Change-Id: I27e8f7b6dbc29232542e3749d8e194efa2ef5209
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3799
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

headers/posix/utmpx.h

@@ -17,7 +17,8 @@ struct utmpx {
 	pid_t			ut_pid;			/* process ID */
 	char			ut_user[32];	/* user login name */
 	char			ut_line[16];	/* device name */
-	char			__ut_reserved[192];
+	char			ut_host[128];	/* remote hostname */
+	char			__ut_reserved[64];
 };