/root: Install .cshrc and .profile links with the same mode.

Previously we would:

1. Install /root/.cshrc and /root/.profile with mode FILESMODE=644 as
   requested in src/etc/root/Makefile and as echoed in
   /etc/mtree/special.

2. Create hard links at /.cshrc and /.profile through CONFIGLINKS.

3. Because LINKSMODE was unset and defaults to NOBINMODE=444, change
   the mode to 444.

This scenario is confusing, and mtree objects to it, which is bad for
warning fatigue in a security-relevant mechanism.  (There are also
several other files mtree objects to out of the box -- we should fix
those too.)

With this change we install the links with the same mode as the
original files, in agreement with the mtree.  The files, .cshrc and
.profile, are intended to be editable configuration files, so 644
makes sense while 444 makes no sense and gets in the way of editors
like vi.

Discussed on tech-userlevel:
https://mail-index.netbsd.org/tech-userlevel/2022/08/29/msg013498.html

XXX pullup-8
XXX pullup-9

etc/root/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.4 2012/11/17 23:08:38 uwe Exp $
+#	$NetBSD: Makefile,v 1.5 2022/08/30 13:14:48 riastradh Exp $
 
 CONFIGFILES=		dot.cshrc dot.klogin dot.login dot.profile dot.shrc
 
@@ -12,5 +12,7 @@ FILESNAME_${F}=		${F:S/dot//}
 CONFIGLINKS=		/root/.cshrc	/.cshrc \
 			/root/.profile	/.profile
 
+LINKSMODE=		${FILESMODE}
+
 .include <bsd.files.mk>
 .include <bsd.links.mk>