added src/chemistry_gpu to the Makefile DIRS list
added src/chemistry_gpu to the Makefile DIRS list

cholla-hydro/cholla,evaneschneider/cholla,evaneschneider/cholla,evaneschneider/cholla,cholla-hydro/cholla,cholla-hydro/cholla,evaneschneider/cholla,cholla-hydro/cholla