add dirent_h (#2958)

* add dirent_h

* Update xmake.lua

packages/d/dirent_h/xmake.lua

@@ -0,0 +1,16 @@
+package("dirent_h")
+    set_kind("library", {headeronly = true})
+    set_homepage("https://github.com/win32ports/dirent_h")
+    set_description("header-only Windows implementation of the <dirent.h> header")
+    set_license("MIT")
+
+    add_urls("https://github.com/win32ports/dirent_h.git")
+    add_versions("2021.09.25", "0170b775ae7cede136c0c1f71b8e5002cc36288b")
+
+    on_install("windows", function (package)
+        os.cp("dirent.h", package:installdir("include"))
+    end)
+
+    on_test(function (package)
+        assert(package:has_cfuncs("opendir", {includes = "dirent.h"}))
+    end)