add pam.d to the subdir list, so an objdir is created for the temp files

that pam.d/Makefile wants to do now days.

Author: mrgtwentythree

etc/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.473 2024/06/23 00:37:12 mrg Exp $
+#	$NetBSD: Makefile,v 1.474 2025/01/01 03:21:10 mrg Exp $
 #	from: @(#)Makefile	8.7 (Berkeley) 5/25/95
 
 # Environment variables without default values:
@@ -716,7 +716,7 @@ snap_md_post: .PHONY check_DESTDIR check_RELEASEDIR snap_post
 clean:
 	-rm -rf ${CDROM.dir} ${CDROM.pathlist} ${OBSOLETE.dir}
 
-SUBDIR=	defaults rc.d mtree
+SUBDIR=	defaults rc.d pam.d mtree
 
 .include <bsd.prog.mk>
 .include <bsd.subdir.mk>