This patchset reduces conntrack memory usage by 32 bytes per conntrack entry
(on x86, about 11%) by removing redundant information and using smaller data
types where possible.

It consists of the following single patches:

1. kill-ip_nat_hash.patch:

Replace struct ip_nat_hash by struct list_head. Saves two
pointers to containing conntrack structure by better use
of list macros.

2. kill-nf_ct_info-array.patch:

Replace struct nf_ct_info array in struct ip_conntrack
by new field in struct sk_buff which indicates relation-
ship between the packet and the conntrack. Saves five
pointers to containing conntrack structure.

3. ip_nat_info-u16.patch:

Use u_int16_t for initialized/num_manips fields in
struct ip_nat_info. Saves 4 bytes.
