Fix a bug when getting a gzip header extra field with inflate(). am: f8b8a9088c am: 2cde1caaff am: 10dfbbc9b2 am: 08ac66a61b

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/zlib/+/20545896

Change-Id: Ie8d47fa3b56c0eae8683bc386f01d35eaa46026a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>