building gobject-introspection with Mingw

[Damon Register <damon w register lmco com>]

I have been experimenting for a little while, trying to build gtk3 using Mingw.
I have done all the packages up to gtk itself.  gtk3 build failed with an error
message about fallback-c89.c.  I found this using Google:
http://osdir.com/ml/commits.gnome/2012-05/msg04658.html

I used the suggested patch.  The downside is that this seems to have required
autoreconf.  Now configure wants gobject-introspection.  I am not sure if this
is because the autoreconf changed something or just because I hadn't got that
far with the fallback problem.  Anyway, I tried building gobject-introspection
and that is where I am stuck now.

At this point, make failed with
    GISCAN GLib-2.0.gir
    env: Files/Microsoft: No such file or directory
I discovered that the build process doesn't like spaces in the PATH so I fixed
the PATH.

The next problem was this error:
    IOError: [Errno 2] No such file or directory: '.\\.libs\\.libs\\_giscanner.pyd'
    Why the double libs?
I found this https://bugzilla.gnome.org/show_bug.cgi?id=620566
so it wasn't hard to find and fix that problem