Fix a bug when getting a gzip header extra field with inflate(). am: f8b8a908 am: 2cde1caa

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



Change-Id: I67b0e6edc4bdd7057903dd8f58abb0c9fdc3a7b7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>