gEDA-dev: windows installers -- push it a bit more

[Ales Hvezda]

[snip]
>  * gschem: Peter Clifton reported success for a crosscompile with Mingw32
>  after some tweaking.

I built (read: hacked up) gschem for w32 and experienced the following issues:

1) it does _not_ really build without some unpleasant hacks and,

2) there are some unacceptable performance issues.  For example: try
dragging (move/copy/place) a _simple_ component around; it will be
extremely choppy and consume 100% of the CPU.

Also, there are issues with guile on w32 related to not being install
relocatable; which is something w32 users expect (ability to install
into any directory on any drive).

-Ales