Can you use `uname -s` instead of OSTYPE? I think it might be more reliable. I've never seen OSTYPE before, although now I see that my shell has it set as well.

Also, could you move this logic down to line 793 (on current master) where we already set the default `MAKE` for all operating systems? Makes sense that all defaults logic goes together.

```
if MAKE is empty
  if FreeBSD
    MAKE=gmake
  else
    MAKE=make
  end
end
```