[zlib] Remove redundant return statement

It's at the end of a void function, so doesn't really do anything.

Bug: none
Change-Id: Id5b7fb2dd3c403a995f2020abdf87d89c2198d1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3968073


Commit-Queue: Adenilson Cavalcanti <cavalcantii@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Reviewed-by: Chris Blume <cblume@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1061900}
NOKEYCHECK=True
GitOrigin-RevId: 38567e4c72b7b83b8063d9097cd405d44661f102