Fix a bug when getting a gzip header extra field with inflate(). am: e5a6e35a am: 35075bc1

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



Change-Id: I5c43285626a8f4142aa94c90ac3bad58fd57fa73
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>