Zix 0.8.0

Zix 0.8.0 has been released. Zix is a lightweight C library of portability wrappers and data structures.

Changes:

• Add ZIX_REALTIME and ZIX_NONBLOCKING attributes
• Add warning suppression macros
• Annotate count and size parameters of allocator API
• Avoid "deprecated" POSIX functions on Windows
• Avoid over-use of yielding meson options
• Clean up attribute documentation
• Gracefully handle failed allocation in path and filesystem functions
• Reduce empty BTree memory requirements
• Strengthen zix_file_equals()
• Use getenv() instead of environ to avoid issues on FreeBSD