Different UID for directories

[Randy Terbush <ra...@zyzzyva.com>]

I received the patch from Michael Kutzner regarding the addition
of what is apparently a CERN feature to be able to seteuid for
specific directories. I'll upload the patch for review later today.

Some comments:

* I'm kind of kept from testing newer versions of Apache since
  I have now developed a dependency on the seteuid() patch submitted
  by Felix Leitner and modified by me to be a runtime option.
  I would really like to see some type of functionality that would
  allow doing seteuid based on file owner/directory....

* This patch again relys on switching to uid 0 to set the effective
  id, and does not do some of the security checks that I have added
  to the Leitner patch.

* The ultimate solution seems to me the change that would allow the
  parent process to manage process pools for virtual hosts. A quick
  glance at the code tells me that we would need to change the server_rec
  structure to store a UID/GID. The port field is already there and
  could probably be used to bind the port for the virtual host being
  configured.

I would very much like to hear comments from others about the possible
snags here. I am going to start hacking at it to see what I break.