py: Fix type of integer in decoding int.

py/vm.c

@@ -157,7 +157,7 @@ dispatch_loop:
                         break;
 
                     case MP_BC_LOAD_CONST_SMALL_INT: {
-                        int num = 0;
+                        machine_int_t num = 0;
                         if ((ip[0] & 0x40) != 0) {
                             // Number is negative
                             num--;