Zabbix

...G...... [ZBX-6565,ZBX-13645,ZBX-14559] fixed agent on AIX 6.1 TL0, 7.1 TL0: system.stat[memory,avm], compilation, crash on net.dns[] items

For ZBX-6565:
   - fixed compilation on AIX 7.1 with a bug in /usr/include/netinet/in6_var.h.
     The bug causes fail of 'libperfstat.h' tests in 'configure' script and
     system.stat[memory,avm] support is not compiled in.
   - improved error message if 'system.stat[memory,avm]' support is not compiled in.

For ZBX-13645:
   - removed dependency on perfstat_partition_config() (it is not available on AIX 7.1 TL0),
     it was replaced with lpar_get_info(() to get number of logical processors in
     a logical partition for system.cpu.num[].
    
For ZBX-14559:
   - fixed crash when when processing net.dns[] items on some AIX systems.