krb5 builds on Windows outside of Pismere

[Jeffrey Altman]

I tried for the first time in a very long time to build krb5 1.3 head on
Windows without pismere and of course it does not complete.  DNS support
is now pretty much mandatory and there simply is no resolver library to
link to without the WSHELPER library provided by Pismere.

Two possible approaches:

   1. make sure the default build on Windows does not have DNS references
   2. add support to use the new Microsoft DNS APIs which are supported
      only on 2000, XP, and 2003

Thoughts?

- Jeff