Create a port for macOS

[lucasvr]

HDF5-UDF is only supported on Linux. The two modifications that currently depend on Linux are (1) scanning of /proc to get a file handle to the underlying HDF5 file and (2) the use of Seccomp + Syscall-Intercept.

[lucasvr]

An initial port for macOS has been introduced by commit 6689226. The three backends (Python, C/C++, and LuaJIT) are supported. The only limitation, for now, is the lack of support for sandboxing.