Snippets for msgpack-c 7.0.1 from Nix aarch64-linux

Sourced from https://hydra.nixos.org/log/hfz7wxbbizgddpxnzk7yk95p4zv1qzgr-msgpack-c-7.0.1.drv.

• /build/source/test/buffer_c.cpp:126:15: warning: ignoring return value of 'ssize_t writev(int, const iovec*, int)' declared with attribute 'warn_unused_result' [-Wunused-result]
    126 |         writev(fd, iov, (int)iovcnt);
        |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~
  

• /build/source/test/buffer_c.cpp:129:13: warning: ignoring return value of 'ssize_t read(int, void*, size_t)' declared with attribute 'warn_unused_result' [-Wunused-result]
    129 |         read(fd, buf, len);
        |         ~~~~^~~~~~~~~~~~~~