minor makefile improvements
minor makefile improvements

saqimtiaz/hesperian-mhealth-pregnancy-warning-signs,saqimtiaz/hesperian-mhealth-pregnancy-warning-signs,saqimtiaz/hesperian-mhealth-pregnancy-warning-signs,saqimtiaz/hesperian-mhealth-pregnancy-warning-signs,saqimtiaz/hesperian-mhealth-pregnancy-warning-signs,saqimtiaz/hesperian-mhealth-pregnancy-warning-signs