Fix readline test after callback changes

This one requires libedit and was probably missed for that reason.

Author: nikic

ext/readline/tests/libedit_callback_handler_install_001.phpt

@@ -14,11 +14,13 @@ function foo() {
 }
 
 var_dump(readline_callback_handler_install('testing: ', 'foo'));
-var_dump(readline_callback_handler_install('testing: ', 'foobar!'));
+try {
+    var_dump(readline_callback_handler_install('testing: ', 'foobar!'));
+} catch (TypeError $e) {
+    echo $e->getMessage(), "\n";
+}
 
 ?>
---EXPECTF--
+--EXPECT--
 bool(true)
-
-Warning: readline_callback_handler_install(): foobar! is not callable in %s on line %d
-bool(false)
+readline_callback_handler_install(): Argument #2 ($callback) must be a valid callback, function "foobar!" not found or invalid function name