[krbdev.mit.edu #3940] Disable MSLSA: ccache in WOW64 on pre-Vista Beta 2 systems

[Jeffrey Altman via RT]

Microsoft did not finish implementing the WOW64 Lsa functions required
for use by the MSLSA: krb5_ccache.   When the Lsa functions are called,
they return success but do not return valid data structures.  As a
result the calling application crashes.

When building 32-bit versions of the krb5 library we must add a version
check to the MSLSA resolve function that prevents the ccache from being
accessed when the operating system is 64-bit Windows and the version
number is less than Vista/LH Beta 2.