Alternative linker win32/64

[dsimcha]

== Quote from Trass3r (un at known.com)'s article
> Sounds fantastic, but what about those rumors that Unilink will become
> commercial sometime?

Well, IMHO the intermediate solution would be to just get DMD to output Win64 OMF
object files for now, and cross the linking bridge when we come to it.  Unilink is
good enough for at least testing that the object files output by DMD are correct,
and should be at least better than nothing until Optlink gets rewritten.