Windows: DriveSubstitution handle too small buffer

Windows: DriveSubstitution handle too small buffer

If the buffer passed to DriveSubstitution is too small the
resulting file path will end up being truncated.  At the very
least log the fact that truncation is occurring.  In addition
return the fact that truncation occurred to the caller.

In NPGetUniversalName allocate a 4K buffer on the heap instead
of calculating a buffer based on the local name buffer size.
The local name buffer size has no relationship with the required
buffer size for the expanded unc or device path.

FIXES 130548

Change-Id: I86fbb9db4aa6a438dbb5e793678ec52283d5546b
Reviewed-on: http://gerrit.openafs.org/6618
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>