deps: update zlib.gyp for zlib 1.2.8
deps: update zlib.gyp for zlib 1.2.8

This adds the new gzip source files to the zlib.gyp The changes are
derived from third_party/zlib/zlib.gyp in the Chromium repository.

Reviewed-By: Bert Belder <9f2ff180696da386c1be31b4507155616db25dc6@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node