include zk_c changes from previous release

- The zookeeper C lib from official source fails to build on smartos for
  a number of reasons, such as redefining htonl which is already
  provided on Solaris. Looks like the previous zk_c in the older release
  was not the official one as it contained a bunch of fixes for building
  on solaris that i can't find. The next version of the C lib 3.4.7 does include fixes for
  solaris but it has yet to be released.

  Carry on using previous version until 3.4.7 is released proper.