On the 1.6.x branch: Fix get-deps.sh for zlib.

* get-deps.sh: Zlib doesn't have 1.2.7 online anymore, and switched to tar.gz.
   Fix this and --record-only merge the corresponding trunk fix (r1477730).


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.6.x@1485439 13f79535-47bb-0310-9956-ffa450edef68