This source has been extracted from the lz4 release tarball, version 1.9.2
released on August 20th, 2019.

The source code originates from the "lib" subdirectory. The license is included
in the subdirectory licenses/LZ4.txt in the tools-ng subdirectory of the
squashfs-tools-ng source package.

The following modifications have been made:
 - Always define LZ4LIB_API and LZ4LIB_STATIC_API to set default visibility to
   hidden, so the LZ4 functions aren't exported from libsquashfs.
 - Remove the streaming functions and most of the functions that aren't used
   by libsquashfs.