Fix isvirtual flag for logging class

Use fact is_virtual to determine the $virtual value

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>
Fix isvirtual case only for checksum_bootpc as well

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>
Merge pull request #757 from bogdando/fix_isvirtual

Fix/add isvirtual fact usage for checksum rules