Windows: Use Shell API for checking file case correctness.

The old method of converting to short 8.3 name and back does
not work for drives where this is disabled.

Change-Id: Ia0a46331a31eeb61578c31ba063a80665d5fc25c
Reviewed-by: Michael Brasser <michael.brasser@live.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>