PORT: Updated zlib version
PORT: Updated zlib version

1.2.5 doesn't compile with Ubuntu 12.10 MinGW toolchain.  1.2.7 does.

mndrix/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,edechter/swipl-devel