zlib library in order to enable support of files larger than 2Gb.
Providing an effective test is hardly possible, since the problem starts
only when archive table becomes larger than 2Gb.


zlib/gzio.c:
  Move include of zutil.h on top of gzio.c to include chain of
  zutil.h->zlib.h->zconf.h->config.h before including anything else.
zlib/zconf.h:
  Includes config.h in order to make _FILE_OFFSET_BITS definition available.