[krbdev.mit.edu #1789] Replacing Windows KRBV4W32.DLL with KRB4_32.DLL

[via RT]

For KfW 3.0, one of the goals is to replace KRBV4W32.DLL with
KRB4_32.DLL built from the Krb5 distribution.  As part of the migration
strategy we will want to build a replacement KRBV4W32.DLL which forwards
most if not all calls to KRB4_32.DLL or KRB5_32.DLL.

Attached is a file "krb4-differences.txt" which enumerates the public
API of both KRBV4W32.DLL and KRB4_32.DLL.  There are three categories:

 * only in KRBV4W32.DLL

 * only in KRB4_32.DLL

 * in both

For the purposes of this migration we can ignore those functions which
exist solely in KRB4_32.DLL as they will remain untouched.

For those functions which exist in both of the DLLs we need to ensure
that the functionality of both functions is identical.  If they are not
we need to decide how they should be merged or document what the
functional changes will be.

For those functions which exist solely in KRBV4W32.DLL we need to decide
how to handle them.  Possible options are:

 * remove the function entirely

 * implement the function as a stub which does nothing

 * add the missing functionality to KRB4_32.DLL 

 * export a previously unexported function from KRB4_32.DLL