Using "DEST" for our build artifacts inside individual bundlescripts was already well-established convention, but this officializes it by having `make.sh` itself set the variable and create the directory, also handling CYGWIN oddities in a single central place (instead of letting them spread outward from `hack/make/binary` like was definitely on their roadmap, whether they knew it or not; sneaky oddities).
Signed-off-by: Andrew "Tianon" Page <admwiggin@gmail.com>
