Zabbix

........S. [ZBXNEXT-3480] expand inventory macros from cache

A new DC_HOST_INVENTORY structure can be used for
retrieving inventory informations from the configuration
cache using the new DCget_host_inventory_by_hostid()
function.
All the inventory informations will be copied from the
structure in cache in the one passed as first argument.

All the functions that took care of performing queries to
the database in src/libs/zbxserver/expression.c for
the inventory data, now use the new structure and
function call for getting the same data from configuration
cache.

The inventory_fields map will now map a macro to an
integer that correspond to the right field in the fields
array of a DC_HOST_INVENTORY structure.