This diagnostic flag, enabled by default in CircuitPython, requires that
nonstatic functions have a previous prototype. Since placing prototypes
in header files is the only way that mismatched arguments between function
definition and use sites can be detected, this is a valuable warning.
In the case of ulab, the majority of the changes required were to mark
functions as "static" that were used only in a single C source file.
- Adapt to signature of mp_make_new_fun_t for mpy and cpy by ifdef
- Use MP_OBJ_IS_TYPE instead of mp_obj_is_type
- Ditto MP_OBJ_IS_INT
- Use mp_const_none instead of MP_ROM_NONE
- Ditto mp_const_true, mp_const_false
