The test/object test is passing again, instead of deadlocking.

The Win32 definitions for LONG, ULONG, etc conflicts with
hb-open-type.h.  Avoid that by making sure hb-object-private.h
and hb-open-type.h are not included in the same compilation unit.

Patch from Bradley Grainger.

Based on patch by Bradley Grainger.

With this, test/object is now passing.  Yay!

Now that we use C++ for all source code, lets benefit from it!

The hb_be_int16/32_get/put/eq() macros grow code size if replaced with
inline functions, so leave them as is.

Would have been nice if gcc had warned...

Makes way for adding arbitrary user_data support.

Unused right now.

So we can liberally use the simple features of C++ that parts of the
codebase is already using.

It's just sugar.

Since we now assert thos in hb-private.h, the int types cannot be wrong.
(Except for when someone else includes hb-common.h in a very broken
configuration, but that's not our problem!)

Plus, we don't use inline in the public headers, so remove that too.

__LOC__ was renamed to _HB__LOC__ in cd7555 but the corresponding
change wasn't made in hb-private.h.

Kinda hand-wavy right now.  Not tested.