configure: add configure check for ntdddisk.h

This header file provides w32 ioctl definitions for working with disk
devices. Older versions of mingw do not expose this in a useable way,
so add a configure check and report it via CONFIG_QGA_NTDDSCSI.

Subsequent patches will use this macro to stub out functionality that
relies on this in cases where it's not available.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
