Convert more upgrade scripts to the new sysctl helper

package/gluon-core/files/lib/gluon/upgrade/core/initial/011-gluon-network

@@ -30,6 +30,3 @@ tl-wdr4300) # fix up duplicate mac addresses
 esac
 
 uci_commit network
-
-echo 'net.ipv6.conf.all.accept_ra=0' >> /etc/sysctl.conf
-echo 'net.ipv6.conf.default.accept_ra=0' >> /etc/sysctl.conf

package/gluon-core/files/lib/gluon/upgrade/core/invariant/011-network

 #!/bin/sh
 
 . /lib/functions.sh
+. /lib/gluon/functions/sysctl.sh
 
 
 uci_set network wan peerdns '0'
 uci_commit network
+
+sysctl_set net.ipv6.conf.all.accept_ra 0
+sysctl_set net.ipv6.conf.default.accept_ra 0

package/gluon-mesh-batman-adv/files/lib/gluon/upgrade/mesh-batman-adv/initial/010-mesh

@@ -16,5 +16,3 @@ fi
 uci_set network client type 'bridge'
 uci_set network client proto 'dhcpv6'
 uci_set network client reqprefix 'no'
-
-echo 'net.ipv6.conf.br-client.forwarding=0' >> /etc/sysctl.conf

package/gluon-mesh-batman-adv/files/lib/gluon/upgrade/mesh-batman-adv/invariant/011-mesh

@@ -2,6 +2,7 @@
 
 . /lib/functions.sh
 . /lib/gluon/functions/sysconfig.sh
+. /lib/gluon/functions/sysctl.sh
 
 
 uci_remove batman-adv bat0
@@ -46,3 +47,6 @@ uci_add dhcp dhcp client
 uci_set dhcp client interface 'client'
 uci_set dhcp client ignore '1'
 uci_commit dhcp
+
+
+sysctl_set net.ipv6.conf.br-client.forwarding 0