Fix a bug when getting a gzip header extra field with inflate(). am: abcfa4a9

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/zlib/+/20545900



Change-Id: I979fe4e49b2ac2b081b8026b12cff113f7d3fa35
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>