Run ftpd regression tests.  The framework runs a client and an ftpd.

SUDO=doas
As ftpd needs root privileges, either run the tests as root or set
this variable and run make as a regular user.  Only the code that
requires it is run as root.

KTRACE=ktrace
Set this variable if you want a ktrace output from ftpd.  Note that
ktrace is invoked after SUDO as SUDO would disable it.

FTPD=/usr/libexec/ftpd
Start an alternative ftpd program that is not in the path.

Requirements:

The test needs the port net/ucspi-tcp and the user "ftp" for anonymous
logins.