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

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



Change-Id: I355d6b707bc1680fb305fcd647a2877cb18755ae
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>