py: Fix builtin abs so it works for bools and bignum.

py/objint.c

@@ -266,6 +266,16 @@ bool mp_obj_int_is_positive(mp_obj_t self_in) {
     return mp_obj_get_int(self_in) >= 0;
 }
 
+// This must handle int and bool types, and must raise a
+// TypeError if the argument is not integral
+mp_obj_t mp_obj_int_abs(mp_obj_t self_in) {
+    mp_int_t val = mp_obj_get_int(self_in);
+    if (val < 0) {
+        val = -val;
+    }
+    return MP_OBJ_NEW_SMALL_INT(val);
+}
+
 // This is called for operations on SMALL_INT that are not handled by mp_unary_op
 mp_obj_t mp_obj_int_unary_op(mp_uint_t op, mp_obj_t o_in) {
     return MP_OBJ_NULL; // op not supported