[ofw] creating common ib_types.h for linux and windows

[Hefty, Sean]

> What is your end goal? To have one code base for OpenSM that would be able to
> be compiled on both Linux and Windows based on __WIN__ definition?

My end goal is to decrease the maintenance cost porting opensm to Windows.  Ideally, I'd like to have a common code base for opensm, similar to what we have for ibmad and ib-diags.  Whether we achieve that using #ifdef's, OS specific header files, some other means (such as a windows specific patches to complete the conversion), or a combination of these, I don't really care.

- Sean