sysctl: Protect hard/symlinks by default.

There is no usecase for not protecting symlinks that I know of in OpenWrt.
Not even on desktop systems where you have multiple users with a shell.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

package/base-files/files/etc/sysctl.d/10-default.conf

@@ -5,6 +5,9 @@ kernel.panic=3
 kernel.core_pattern=/tmp/%e.%t.%p.%s.core
 fs.suid_dumpable=2
 
+fs.protected_hardlinks=1
+fs.protected_symlinks=1
+
 net.ipv4.conf.default.arp_ignore=1
 net.ipv4.conf.all.arp_ignore=1
 net.ipv4.ip_forward=1