Blender Git Loki

I went whole hog on the definitions each platform has its own block
and there is a block at the very end for platforms not specified above.

(not all of the defintions are in the platform's for example there
is no need for export NAN_IKSOLVER ?= $(LCGDIR)/iksolver
to be repeated all over the place, all of the ones you'll probably
want to change are in the platform specific blocks though)

This allows all platforms to be overridden by env vars...

Kent