Run httpd regressions tests.  The framework runs a client and a httpd.
Each test creates a special httpd.conf and starts those two processes.
All processes write log files that are checked for certain messages.
The test arguments are kept in the args-*.pl files.

SUDO=sudo
As httpd 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 httpd.  Note that
ktrace is invoked after sudo as sudo would disable it.

HTTPD=/usr/src/usr.sbin/httpd/obj/httpd
Start an alternative httpd program that is not in the path.

HTDOCS_SPARSE=no
Set to anything other than "yes" to create real test files instead of
sparse files.  This needs more than 1G of free disk space.