xxhash: upgrade 0.8.1 -> 0.8.2

xxhash: upgrade 0.8.1 -> 0.8.2

Changelog:
==========
- fix  : XXH3 S390x vector implementation
- fix  : PowerPC vector compilation with IBM XL compiler
- perf : improved WASM speed by x2/x3 using SIMD128
- perf : improved speed (+20%) for XXH3 on ARM NEON
- cli  : Fix filename contain /LF character
- cli  : Support # comment lines in --check files
- cli  : Support commands --binary and --ignore-missing
- build: fix -Og compilation
- build: fix pkgconfig generation with cmake
- build: fix icc compilation
- build: fix cmake install directories
- build: new build options XXH_NO_XXH3, XXH_SIZE_OPT and XXH_NO_STREAM to reduce binary size
- build: dedicated install targets
- build: support DISPATCH mode in cmake
- portability: fix x86dispatch when building with Visual + clang-cl
- portability: SVE vector implementation of XXH3
- portability: compatibility with freestanding environments, using XXH_NO_STDLIB
- portability: can build on Haiku
- portability: validated on m68k and risc-v
- doc  : XXH3 specification
- doc  : improved doxygen documentation
- misc : dedicated sanity test binary

License-Update: Copyright year updated to 2021

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>