[win32][added] Hybrid shutdown on Windows 8

Do a hybrid shutdown on Windows 8+ (which in turn enables quick boot). This is what the standard Windows shutdown command does and as a user I expect XBMC to do the same.

Actually Microsoft managed to do this in a non-backwards compatible fashion so I have to check the OS version before flagging ExitWindowsEx. Also our standard build environment does not know about EWX_HYBRID_SHUTDOWN so I just used its hex equivalent.

Tested on Windows XP Prof 32 bit, Windows 7 Home Premium 64-bit and Windows 8 Pro 64-bit.