[zlib] Apply https://github.com/madler/zlib/pull/898

This fixes an incorrect assertion, see
https://github.com/madler/zlib/issues/897

The PR has been accepted upstream, but isn't published as part of the
'develop' branch yet.

Bug: 1511987
Change-Id: Icedb1ff619acec63d655b54bb65d25918b7e240a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5131006


Reviewed-by: Nico Weber <thakis@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1238580}
NOKEYCHECK=True
GitOrigin-RevId: 1742eed8819e3862dcb4a618be1dca482908f365