Follow the same format as other ports using the macro to include
the HAL header.

This gets uPy readline working with unix port, with tab completion and
history.  GNU readline is still supported, configure using
MICROPY_USE_READLINE variable.

Reference MCU is dsPIC33J256GP506 with 256k ROM and 8k RAM, on the dsPIC
DSC Starter Kit board.  The REPL works, GC works, pyb module has LED and
Switch objects.  It passes some tests from the test suite (most it can't
run because it doesn't have the Python features enabled).

Now all ports can use pybstdio.c to provide sys.stdin/stdout/stderr, so
long as they implement mp_hal_stdin_* and mp_hal_stdout_* functions.