Need of clear_environment()

[Havoc Pennington]

clear_environment is used in the launch helper which is configured in
the system.conf:

  <!-- This is a setuid helper that is used to launch system services -->
  <servicehelper>@DBUS_LIBEXECDIR@/dbus-daemon-launch-helper</servicehelper>

You can change to a different helper or omit the helper if you like.

The purpose of clearing the environment is that we're messing with
setuid stuff, and trying to avoid potential security problems.

Havoc