Windows: CM_ERROR_INEXACT_MATCH is not a fatal error

Windows: CM_ERROR_INEXACT_MATCH is not a fatal error

cm_BPlusDirLookup() and cm_Lookup() can return CM_ERROR_INEXACT_MATCH
which is not a fatal error.  Instead it is an indication that the returned
cm_scache object was not a case sensitive match.  Do not fail the request
and do not leak the cm_scache reference.

Change-Id: Ieef3ce1ac96a8794859b5b9c530545d4fdd26bd5
Reviewed-on: http://gerrit.openafs.org/12057
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>