lz4: updated to 1.9.4

v1.9.4:
perf : faster decoding speed (~+20%) on Apple Silicon platforms, by @zeux
perf : faster decoding speed (~+70%) for -BD4 setting in CLI
api : new function LZ4_decompress_safe_partial_usingDict() by @yawqi
api : lz4frame: ability to provide custom allocators at state creation
api : can skip checksum validation for improved decoding speed
api : new experimental unit lz4file for file i/o API, by @anjiahao1
api : new experimental function LZ4F_uncompressedUpdate(), by @alexmohr
cli : --list works on stdin input, by @Low-power
cli : --no-crc does not produce (compression) nor check (decompression) checksums
cli : fix: --test and --list produce an error code when parsing invalid input
cli : fix: support skippable frames when passed via stdin, reported by @davidmankin
build: fix: Makefile respects CFLAGS directives passed via environment variable
build: LZ4_FREESTANDING, new build macro for freestanding environments, by @t-mat
build: make and make test are compatible with -j parallel run
build: AS/400 compatibility, by @jonrumsey
build: Solaris 10 compatibility, by @pekdon
build: MSVC 2022 support, by @t-mat
build: improved meson script, by @eli-schwartz
doc : Updated LZ4 block format, provide an "implementation notes" section

(adam)