Compatibility with existing code

A libc mode that uses I/O streams and I/O arrays will be able to support:

• read, write, pread, pwrite
  • and everything build around them
• all non-I/O things
• lseek
• Emulation for open, mmap, socket, etc.

Continue to support the libc mode that uses wasi-filesystem and wasi-sockets.

Let developers chose!