Fix gzip to deal with CRC's being signed values in Python 2.x properly and to read 32bit values as unsigned to start with rather than applying signedness fixups allover the place afterwards.
Fix gzip to deal with CRC's being signed values in Python 2.x properly and to
read 32bit values as unsigned to start with rather than applying signedness
fixups allover the place afterwards.

This hopefully fixes the test_tarfile failure on the alpha/tru64 buildbot.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator