Proposal, different archs as leaf sub-folders.

[mingw android]

Hi,

Following on from hacking about with getting the platform plugins to
work, and given that we're going for x86 support too, I think it might
make sense to do the different arches through leaf level folders as
opposed to top level folders. It would save duplication of some common
things (headers and mkspecs for example). I'm sure there'd be a few
technical issues to overcome, but I think it might be worthwhile.

Anyone got opinions on this? I guess it's not something that's
pressing at all though so I'd put it on the back-burner.

Cheers,

Ray.