py/objint: Convert mp_uint_t to size_t where appropriate.

py/objint.c

@@ -291,7 +291,7 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 }
 
 // This is called only with strings whose value doesn't fit in SMALL_INT
-mp_obj_t mp_obj_new_int_from_str_len(const char **str, mp_uint_t len, bool neg, mp_uint_t base) {
+mp_obj_t mp_obj_new_int_from_str_len(const char **str, size_t len, bool neg, unsigned int base) {
     mp_raise_msg(&mp_type_OverflowError, "long int not supported in this build");
     return mp_const_none;
 }