imagehlp/tests: Add test for BindImageEx

[Bernhard Reiter]

Still struggling to get my first patch ready to be committed. I've
removed all the typecasts I was able to, fixed variable names, and tried
to initialize variables whereever required, as told by people on
#winehackers.

Having been told on that channel to only post to wine-patches@ after
having the patch reviewed on this list, I'd be grateful for a (hopefully
final) review.

Bernhard