various makefile refinements for better supporting native Windows builds
various makefile refinements for better supporting native Windows builds

minor-jason/avian,ucdseniordesign/avian,joshuawarner32/avian,MaartenR/avian,marcinolawski/avian,lostdj/avian,minor-jason/avian,badlogic/avian,bgould/avian,getlantern/avian,lostdj/avian,getlantern/avian,bgould/avian,dicej/avian,badlogic/avian,bigfatbrowncat/avian-pack.avian,bgould/avian,marcinolawski/avian,joshuawarner32/avian,lwahlmeier/avian,bigfatbrowncat/avian-pack.avian,ucdseniordesign/avian,joshuawarner32/avian,joshuawarner32/avian,lwahlmeier/avian,MaartenR/avian,bigfatbrowncat/avian-pack.avian,getlantern/avian,badlogic/avian,lwahlmeier/avian,dicej/avian,ucdseniordesign/avian,badlogic/avian,lostdj/avian,getlantern/avian,dicej/avian,minor-jason/avian,marcinolawski/avian,ucdseniordesign/avian,bigfatbrowncat/avian-pack.avian,MaartenR/avian,MaartenR/avian,lostdj/avian,marcinolawski/avian,lwahlmeier/avian,bgould/avian,dicej/avian,minor-jason/avian