Outstanding issues with NFS client

[JE-Archer]

• os.listdir() on some directories causes a crash (IP=NULL), e.g. os.listdir('content/images').
• need a proper asynchronous client library
• need examples in the README on how to use it
• dependency on libgcc
• libnfs doesn't work with clang
• libnfs doesn't build on macos due to unsupported flag
• some stuff not implemented, e.g. file modes
  - [ ] using musl instead of our own libc This is it's own GitHub issue Integrate standard libc #48
• musl calls into gettime() to get real-time clock, but we don't have an rtc
• unsure of memory lifetimes of libnfs, i.e. how robust is our heap management to long-running sessions?
• unsure of socket lifetimes, i.e. do we need to do anything extra to handle disconnects/reconnects etc?
• after leaving the Kitty example open for a while, nfs: tcp.c:331:socket_recv_callback: closing connection... appears...