and use a new flag, SUDO_DEBUG_FILENO to specify when to use it.
This allows consumers of sudo_debug_printf() to log that data without
having to specify it manually.
hooks for getenv, putenv, setenv and unsetenv. This makes it
possible for the plugin to trap changes to the environment made by
authentication methods such as PAM or BSD auth so that such changes
are reflected in the environment passed back to sudo for execve().
