Fix a bug when getting a gzip header extra field with inflate(). am: 5abcd199

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/zlib/+/20545971



Change-Id: I889eca7e5ec842e8427587e61e262fb68bc31b5e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>