[NETNS][IPV6]: Make bindv6only sysctl per namespace.

This patch moves the bindv6only sysctl to the network namespace
structure. Until the ipv6 protocol is not per namespace, the sysctl
variable is always from the initial network namespace.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv6.h

@@ -11,6 +11,7 @@ struct netns_sysctl_ipv6 {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header *table;
 #endif
+	int bindv6only;
 };
 
 struct netns_ipv6 {