Code review responses

* Always destroy zval
* Fix all-caps null
* Use EXTENSIONS section in test

Author: tstarling

ext/libxml/libxml.c

@@ -840,10 +840,8 @@ static PHP_RINIT_FUNCTION(libxml)
 static PHP_RSHUTDOWN_FUNCTION(libxml)
 {
 	LIBXML(entity_loader).fci.size = 0;
-	if (!Z_ISNULL(LIBXML(entity_loader).callback)) {
-		zval_ptr_dtor_nogc(&LIBXML(entity_loader).callback);
-		ZVAL_NULL(&LIBXML(entity_loader).callback);
-	}
+	zval_ptr_dtor_nogc(&LIBXML(entity_loader).callback);
+	ZVAL_NULL(&LIBXML(entity_loader).callback);
 
 	return SUCCESS;
 }
@@ -1079,7 +1077,7 @@ PHP_FUNCTION(libxml_set_external_entity_loader)
 		fci.object = NULL;
 		fci.named_params = NULL;
 		if (zend_fcall_info_init(callback, 0, &fci, &fcc, NULL, &error) != SUCCESS) {
-			zend_argument_type_error(1, "must be a valid callback or NULL, %s", error);
+			zend_argument_type_error(1, "must be a valid callback or null, %s", error);
 			RETURN_THROWS();
 		}
 		LIBXML(entity_loader).fci = fci;

ext/libxml/tests/libxml_get_external_entity_loader.phpt

@@ -1,7 +1,7 @@
 --TEST--
 libxml_get_external_entity_loader() returns current handler
---SKIPIF--
-<?php if (!extension_loaded('dom')) die('skip dom extension not available'); ?>
+--EXTENSIONS--
+libxml
 --FILE--
 <?php
 

ext/libxml/tests/libxml_set_external_entity_loader_error2.phpt

@@ -11,4 +11,4 @@ try {
 }
 ?>
 --EXPECT--
-Exception: libxml_set_external_entity_loader(): Argument #1 ($resolver_function) must be a valid callback or NULL, function "nonexistent_function" not found or invalid function name
+Exception: libxml_set_external_entity_loader(): Argument #1 ($resolver_function) must be a valid callback or null, function "nonexistent_function" not found or invalid function name