Embed host liblz4.so in target_files

This file will be used by OTA generator to compress generated patches.
We need the host copy of LZ4 to ensure that compressed bytes matches
what the device would get if the compression were to be done on device.
For more details see go/lz4diff

Bug: 206729162
Test: m dist

Change-Id: I9c4ab772b001bf47da75cb87b028a1f27e2321a8