Cast away compiler warning on Windows.

storage/innobase/handler/ha_innodb.cc:
  Cast away a compiler warning; some functions return ulong or ulint for
  errors, and some use int.  Let's hope these all fit in an int.

storage/innobase/handler/ha_innodb.cc

@@ -3538,7 +3538,7 @@ ha_innobase::write_row(
 				err = innobase_set_max_autoinc(auto_inc);
 
 				if (err != DB_SUCCESS) {
-					error = err;
+					error = (int) err;
 				}
 			}
 			break;