ext/gd create gd object with zend_object_alloc (php#17823)

while at it, fix build warning "wrong" calloc arguments order

Author: devnexen

ext/gd/gd.c

@@ -167,9 +167,7 @@ PHP_GD_API gdImagePtr php_gd_libgdimageptr_from_zval_p(zval* zp)
 
 zend_object *php_gd_image_object_create(zend_class_entry *class_type)
 {
-	size_t block_len = sizeof(php_gd_image_object) + zend_object_properties_size(class_type);
-	php_gd_image_object *intern = emalloc(block_len);
-	memset(intern, 0, block_len);
+	php_gd_image_object *intern = zend_object_alloc(sizeof(php_gd_image_object), class_type);
 
 	zend_object_std_init(&intern->std, class_type);
 	object_properties_init(&intern->std, class_type);

ext/gd/libgd/gd.c

@@ -3190,8 +3190,8 @@ int gdImagePaletteToTrueColor(gdImagePtr src)
 		// Note: do not revert back to gdMalloc() below ; reason here,
 		// due to a bug with a certain memory_limit INI value treshold,
 		// imagepalettetotruecolor crashes with even unrelated ZendMM allocations.
-		// See GH-17772 for an use case.
-		src->tpixels = (int **) gdCalloc(sizeof(int *), sy);
+		// See GH-17772 for a use case.
+		src->tpixels = (int **) gdCalloc(sy, sizeof(int *));
 		if (src->tpixels == NULL) {
 			return 0;
 		}