theme-util.c: fix segfault on attempt to delete custom theme

fixes #334

Signed-off-by: Zhang Xianwei <zhang.xianwei8@zte.com.cn>

Author: zhangxianwei8

capplets/appearance/theme-util.c

@@ -99,8 +99,8 @@ gboolean theme_delete (const gchar *name, ThemeType type)
       break;
 
     case THEME_TYPE_META:
-      theme = (MateThemeCommonInfo *) mate_theme_info_find (name);
-      theme_dir = g_strdup (theme->path);
+      theme = (MateThemeCommonInfo *) mate_theme_meta_info_find (name);
+      theme_dir = g_path_get_dirname (theme->path);
       del_empty_parent = FALSE;
       break;