bzip2 Add download mirror (#6851)

packages/b/bzip2/xmake.lua

@@ -2,7 +2,8 @@ package("bzip2")
     set_homepage("https://sourceware.org/bzip2/")
     set_description("Freely available, patent free, high-quality data compressor.")
 
-    add_urls("https://sourceware.org/pub/bzip2/bzip2-$(version).tar.gz")
+    add_urls("https://sourceware.org/pub/bzip2/bzip2-$(version).tar.gz",
+             "https://pub.sortix.org/mirror/bzip2/bzip2-$(version).tar.gz")
     add_versions("1.0.8", "ab5a03176ee106d3f0fa90e381da478ddae405918153cca248e682cd0c4a2269")
 
     if is_plat("mingw") and is_subhost("msys") then