add wjakob_filesystem (#4506)

packages/w/wjakob_filesystem/xmake.lua

@@ -0,0 +1,24 @@
+package("wjakob_filesystem")
+
+    set_kind("library", {headeronly = true})
+    set_homepage("https://github.com/wjakob/filesystem")
+    set_description("A tiny self-contained path manipulation library for C++")
+    set_license("BSD-3-Clause")
+
+    add_urls("https://github.com/wjakob/filesystem.git")
+    add_versions("2021.10.28", "c5f9de30142453eb3c6fe991e82dfc2583373116")
+
+    on_install(function (package)
+        os.cp("filesystem", package:installdir("include"))
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include <filesystem/path.h>
+            void test() {
+                filesystem::path path1{"dir1"};
+                filesystem::path path2{"dir2"};
+                auto path3 = path1 / path2;
+            }
+        ]]}, {configs = {languages = "c++11"}}))
+    end)