unzip: fix gcc 15 (#7339)

* unzip: validate existing issue

* `set_languages("gnu17")`

packages/u/unzip/xmake.lua

@@ -1,5 +1,4 @@
 package("unzip")
-
     set_kind("binary")
     set_homepage("http://infozip.sourceforge.net/UnZip.html")
     set_description("UnZip is an extraction utility for archives compressed in .zip format.")
@@ -15,6 +14,7 @@ package("unzip")
             includes("@builtin/check")
             check_cfuncs("HAVE_LCHMOD", "lchmod", {includes = "sys/stat.h"})
             target("unzip")
+                set_languages("gnu17")
                 set_kind("binary")
                 if not has_config("__HAVE_LCHMOD") then
                     add_defines("NO_LCHMOD")