Extend GZIP conditional

[stoeckmann]

If gzip support has been disabled during compilation then also consider gzip relevant states as invalid in deflateStateCheck.

Also the gzip state definitions can be removed.

This change leads to failure in test/example, and I am not sure what the GZIP conditional is trying to achieve. All gzip related functions are still defined in zlib.h

Alternative approach is to remove the GZIP define.