netfilter: x_tables: add unmerged changes

In the commit:
15061668 Merge 3.18.37 into android-3.18

The following commits was skipped in the files:
net/ipv4/netfilter/arp_tables.c
net/ipv4/netfilter/ip_tables.c
net/ipv6/netfilter/ip6_tables.c

62e6fd20 netfilter: x_tables: add and use xt_check_entry_offsets
dda46754 netfilter: x_tables: kill check_entry helper
7ef13f49 netfilter: x_tables: add compat version of xt_check_entry_offsets
7ef13f49 netfilter: x_tables: check for bogus target offset

Change-Id: Ia1833950282df3dc5ef3a6f2185ef3d5f814410c
Signed-off-by: mifl <mifl.pc@gmail.com>