[8u20] approval request for JDK-8044725: Bug in zlib 1.2.5 prevents inflation of some gzipped files

[Xueming Shen]

Hi,

Please approve backport of the following fix from 9 to 8u20, the changeset (upgrade
zlib version from 1.2.5 to 1.2.8) is the same.

Issue:
     https://bugs.openjdk.java.net/browse/JDK-8044725
JDK9 webrev:
http://cr.openjdk.java.net/~sherman/8044725/webrev
JDK8u webrev:
     http://cr.openjdk.java.net/~sherman/8044725/8u20/webrev/

Thanks!
-Sherman