[3/3] scrrun: Implement filesys_GetDrive for local drives.

[Nikolay Sivov]

On 15.10.2015 13:56, Joachim Priesner wrote:
> +        DriveSpec[0] = toupperW(DriveSpec[0]);
> +        if (DriveSpec[0] < 'A' || DriveSpec[0] > 'Z'
> +                || (len >= 2 && DriveSpec[1] != ':')
> +                || (len == 3 && DriveSpec[2] != '\\'))
> +            return E_INVALIDARG;
> +        hr = filesys_DriveExists(iface, DriveSpec, &drive_exists);

I'm not sure about that sanity check, the reason is that DriveExists 
doesn't fail on invalid drivespec?

Also please use method wrappers internally, instead of calling 
implementation functions, I'm talking about filesys_DriveExists.