install: Fix METALOG ouptut for numeric -o and -g args

install's -o and -g flags both accept a name or a numeric argument.
In -U -M (non-root METALOG) mode it always emitted uname= and gname= in
the METALOG, but these are not appropriate for numeric IDs.

If the -o and/or -u arguments parse as an ID, emit uid= and/or gid=
respectively.

Note that if an argument is valid as both a name and numeric ID we will
prefer the name in normal (non -U -M) mode and the ID in -U -M mode.  We
don't want to require a passwd db in non-root mode, and entirely-numeric
user or group names are a terrible idea so just accept this discrepancy.

PR:		284119
Reviewed by:	jlduran
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D48504

(cherry picked from commit 4b04f5d)
(cherry picked from commit 90702fb)

usr.bin/xinstall/xinstall.c

@@ -1410,10 +1410,22 @@ metadata_log(const char *path, const char *type, struct timespec *ts,
 	p = buf;
 	/* Print details. */
 	fprintf(metafp, ".%s%s type=%s", *p ? "/" : "", p, type);
-	if (owner)
-		fprintf(metafp, " uname=%s", owner);
-	if (group)
-		fprintf(metafp, " gname=%s", group);
+	if (owner) {
+		id_t id;
+
+		if (parseid(owner, &id))
+			fprintf(metafp, " uid=%jd", (intmax_t)id);
+		else
+			fprintf(metafp, " uname=%s", owner);
+	}
+	if (group) {
+		id_t id;
+
+		if (parseid(group, &id))
+			fprintf(metafp, " gid=%jd", (intmax_t)id);
+		else
+			fprintf(metafp, " gname=%s", group);
+	}
 	fprintf(metafp, " mode=%#o", mode);
 	if (slink) {
 		strsnvis(buf, buflen, slink, VIS_CSTYLE, extra);