Bareos fixes to fastlzlib

We are currently writing some patches to be able to use the 3 compression algorithms of fastlzlib in an OpenSource backup solution named Bareos which is a an 100% AGPL based clone of the former Bacula backup software. While developing the new feature we
ran into some small problems with linking from Bareos (C++) and with the resetting of
its state which seems to work sightly different then what zlib does and as it tries to be
a compatible API we think it makes sense to fix that.