Fix a bug when getting a gzip header extra field with inflate(). am: e5a6e35a

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/zlib/+/20545899



Change-Id: I2fd5d67f6ec039124388ee0ddba6533b221f9220
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>