[Wxruby-dev] Changed extconf.rb

[Kevin Smith]

I've updated extconf.rb to create a Makefile that can create a 'depends'
file, and it launches 'make depends' as the last step in its process. I
have intentionally not checked in my depends file, since it got built
with hard paths like /usr/lib/ruby/1.6/i386-linux/config.h

I'm not sure if that's proper behavior for an extconf.rb script. Perhaps
someone who's more familiar with extconf.rb could take a look. 

Also, the way I build the depends file is pretty dependent on gcc, so if
anyone knows a cleaner way, I'd appreciate knowing that as well.

I want to keep this compatible with Windows, but I don't have a Windows
box to test with.

The problem is that without knowing dependencies, the project cannot
possibly be built from scratch. This is because bitmap.o should depend
on window.h, which in turn should depend on window.t. If those
dependencies aren't specified, bitmap.o can't be built until after
window.o has been built.

Kevin