benchmarks/lzbench: try to unbreak the port's build against newer Clang

As of September 2023 (llvmorg-18.1.0-rc1) /usr/include/c++/v1/__config
no longer includes <sys/endian.h>, because both Clang and GCC always
define BYTE_ORDER macro. This had accidentally revealed a problem
in Kanzi data compressor which was including <machine/endian.h> to no
avail. Replace it with <sys/endian.h> to obtain bswap??() definitions.

Reported by: pkg-fallout
PR: 285285
LLVM commit: https://github.com/llvm/llvm-project/commit/0a97720