Fix server_aliases handling

Because

  ServerName muskatas.pov.lt
  ServerAlias m
  ServerAlias u
  ServerAlias s
  ServerAlias k
  ServerAlias a
  ServerAlias t
  ServerAlias a
  ServerAlias s
  ServerAlias
  ServerAlias m
  ServerAlias u
  ServerAlias s
  ServerAlias k
  ServerAlias a
  ServerAlias t
  ServerAlias a
  ServerAlias s
  ServerAlias .
  ServerAlias l
  ServerAlias a
  ServerAlias n

is just too funny.