Upgrade lz4 to v1.9.4 am: 996c91caed am: d401c43615

Original change: https://android-review.googlesource.com/c/platform/external/lz4/+/2242764

Change-Id: I07345ef13c88ab0adebfea94b55a67454b085c27
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>