Zabbix

...G...... [ZBX-20525] fixed vfs.dir.size performance issues when walking through directory that has a lot of subdirs/files

Merge in ZBX/zabbix from feature/ZBX-20525-6.5-1 to master

* commit 'f537bac171d9a9c824a0faba23c027a7406af320':
  ...G...... [ZBX-20525] simplified duplicate hardlink map type
  ...G...... [ZBX-20525] added comment
  ...G...... [ZBX-20525] fixed reg file check
  ...G...... [ZBX-20525] added link count check
  .......... [ZBX-20525] added changelog
  ...G...... [ZBX-20525] fixed vfs.dir.size performance issues when walking through directory that has a lot of subdirs/files