_XData32 and _XRead32 don't exist as real functions in 32-bit versions
of these libraries, these end up just being defines that redirect to the
non-suffixed versions of the functions.
Noticed this while tinkering around and is easy enough to solve today.
This function must be able to handle both guest heap pointers *and* host heap
pointers, so it only forwards to the native host library for the latter.
This is because Xlibint users allocate memory using internal macros aliasing
to libc's malloc but then they free using the function XFree. For libX11,
this is not a problem since the allocation happens in a thunked API function
(and hence on the host heap), but if a function from an unthunked library
accesses Xlibint, it will allocate on the guest heap.
One notable example where this was encountered is XF86VidModeGetAllModeLines.
Ryan Houdek