ipvs: HUP processing refactored

copy_srv_states is removed: we can copy states with existing clear_diff_*
functions, as long as clear_diff_services is called before the init_services.

vs_exist, rs_exist: remove side-effects from these functions.
Now they do only search and return pointers.

get_rs_list removed: the new rs list is now passed to clear_diff_rs

init_service_vs: quorum_state assignment is not needed here. It is already assigned either by vs constructor, or by alpha handler, or by clear_diff_services.
ipvs, bug: vs_groups lose quorum on config reload

The commit 7bf6fc contained a bad try to fix the issue
when an alive RS does not appear in a new VSG entry on reload.

This commit fixed the issue properly, and also the case when
RS in VSG is in inhibit mode.
link vsg structure to vs

this adds a pointer to virtual_server_group_t into
the virtual_server_t structure and fills these pointers
after config load.

This change will allow to access vsg items of a vs easily,
without iterating and name compare.
ipvs, refactoring: use links to vs->vsg links

ipvs_cmd: removed vs_group list parameter. Link to vsg is obtained via vs->vsg.

These functions are also modified in the same way:
ipvs_group_cmd, clear_service_rs, clear_service_vs, clear_diff_rs.

clear_diff_vsg: new_vs is passed as a param, vsg pointers are retrieved w/o iterating
genhash: fix path to headers in Makefile
in-progress
in-progress 2