Merge remote-tracking branch 'upstream/master'

* upstream/master: (37 commits)
  [Fix] Fix build
  [Feature] Propagate HTTP result string when using proxy
  [Feature] Better lua_redis logging
  [Fix] Do not greylist messages if redis has failed somehow
  [Feature] Better deal with backend errors
  [Fix] Fix more issues with scripts processing
  [Fix] Fix lua compare function init
  [Fix] Fix proxying of the encrypted messages
  [Fix] Adjust body/body_buf when stealing encrypted message
  [Fix] Properly init and free session structures
  [Fix] Another try to fix hanged redis sessions
  [Minor] Print task pointer to simplify debug
  [Feature] Implement compare scripts for mirrors results
  [Feature] Implement compare scripts setup
  [Feature] Implement mirroring in rspamd proxy
  [Feature] Add method to copy message from http connection
  [Feature] Add utility function to return random number from 0 to 1
  [Feature] Add results parsing code
  [Rework] Separate method to close backend connections
  [Feature] Split main connection from mirrored connections
  ...