Standard I/O library for cl-stream using cffi-unistd as a backend.
Depends on :
Returns an existing UNISTD-INPUT-STREAM or creates one reading from UNISTD:+STDIN-FILENO+.
Returns an existing UNISTD-OUTPUT-STREAM or creates one writing to UNISTD:+STDOUT-FILENO+.
Returns an existing UNISTD-OUTPUT-STREAM or creates one writing to UNISTD:+STDERR-FILENO+.