Fix a bug when getting a gzip header extra field with inflate(). am: 1c4806af am: 9166f7db

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/zlib/+/20545926



Change-Id: Ib5b73455981d0eb45d303e152f8286d1affc8f0f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>