update makefile.am
update makefile.am

add stb_image

mateunho/pal,Adamszk/pal3,mateunho/pal,mateunho/pal,debug-de-su-ka/pal,olajep/pal,RafaelRMA/pal,parallella/pal,parallella/pal,debug-de-su-ka/pal,eliteraspberries/pal,olajep/pal,Adamszk/pal3,aolofsson/pal,mateunho/pal,8l/pal,Adamszk/pal3,RafaelRMA/pal,parallella/pal,parallella/pal,aolofsson/pal,debug-de-su-ka/pal,aolofsson/pal,eliteraspberries/pal,RafaelRMA/pal,olajep/pal,mateunho/pal,debug-de-su-ka/pal,8l/pal,parallella/pal,aolofsson/pal,Adamszk/pal3,eliteraspberries/pal,RafaelRMA/pal,8l/pal,8l/pal,eliteraspberries/pal,debug-de-su-ka/pal,olajep/pal,eliteraspberries/pal