tools/pic32prog: cleanup and allow Makefile to be used standalone
tools/pic32prog: cleanup and allow Makefile to be used standalone

kYc0o/RIOT,OlegHahm/RIOT,kYc0o/RIOT,authmillenon/RIOT,miri64/RIOT,authmillenon/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,authmillenon/RIOT,OlegHahm/RIOT,ant9000/RIOT,ant9000/RIOT,authmillenon/RIOT,miri64/RIOT,jasonatran/RIOT,OTAkeys/RIOT,jasonatran/RIOT,kYc0o/RIOT,miri64/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,ant9000/RIOT,jasonatran/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,OTAkeys/RIOT,jasonatran/RIOT,OTAkeys/RIOT,kaspar030/RIOT,jasonatran/RIOT,kaspar030/RIOT,OTAkeys/RIOT,kYc0o/RIOT,kaspar030/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,ant9000/RIOT,miri64/RIOT