iptables: Constify option struct

iptables: Constify option struct

The struct of type option is only used to initialise a field inside
the xtables_globals struct and is not modified anywhere.
Done using following coccinelle semantic patch

@r1 disable optional_qualifier@
identifier s,i;
position p;
@@

static struct option i@p[] ={...};

@ok1@
identifier r1.i;
expression e;
position p;
@@
e = i@p

@bad@
position p != {r1.p,ok1.p};
identifier r1.i;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r1.i;
@@
static
+const
struct option i[] = { ... };

Signed-off-by: Harsha Sharma <harshasharmaiitr@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>