Roll Zlib from ce5a169f5017 to 6f9b4e619240 (9 revisions)

https://chromium.googlesource.com/chromium/src/third_party/zlib.git/+log/ce5a169f5017..6f9b4e619240

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/zlib-pdfium
Please CC andyphan@google.com,thestig@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Bug: None
Tbr: andyphan@google.com
Change-Id: I18d35ef514c58aacb1ab03cfdd1cb33475db847b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/131491
Bot-Commit: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 9a74ca0..f798976 100644
--- a/DEPS
+++ b/DEPS
@@ -232,7 +232,7 @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling zlib
   # and whatever else without interference from each other.
-  'zlib_revision': 'ce5a169f50174a2be18c38cd7b2a1bf858649e58',
+  'zlib_revision': '6f9b4e61924021237d474569027cfb8ac7933ee6',
 }
 
 # Only these hosts are allowed for dependencies in this DEPS file.