clean up zip support code in pyximport trying to remove some redundancy
clean up zip support code in pyximport trying to remove some redundancy

da-woods/cython,da-woods/cython,scoder/cython,scoder/cython,da-woods/cython,da-woods/cython,cython/cython,fabianrost84/cython,ChristopherHogan/cython,ChristopherHogan/cython,scoder/cython,cython/cython,cython/cython,fabianrost84/cython,fabianrost84/cython,fabianrost84/cython,fabianrost84/cython,ChristopherHogan/cython,cython/cython,scoder/cython