Add LZ4 support

+ crypto: Add lz4 Cryptographic API. ported from
(https://github.com/faux123/htc-m7/commit/da91769e5bee2d580a5886dbfba166b8bd45ee38)
+ lib: Add support for LZ4-compressed kernel. ported from
(https://github.com/faux123/htc-m7/commit/b8d285860f432faa121731c2719ac8068192e7ce)
+ LZ4: compression/decompression signedness mismatch (v2). ported from
(https://github.com/faux123/htc-m7/commit/c0422538477e9be0d064f8c6a45d579a7416c7a8)