pocketfft: add package (#2404)

* pocketfft: add package

* add license

* improve description

packages/p/pocketfft/xmake.lua

@@ -0,0 +1,25 @@
+package("pocketfft")
+    set_kind("library", {headeronly = true})
+    set_homepage("https://github.com/mreineck/pocketfft")
+    set_description("FFT implementation based on FFTPack, but with several improvements")
+    set_license("BSD-3-Clause")
+
+    add_urls("https://github.com/mreineck/pocketfft.git")
+    add_versions("2023.02.14", "076cb3d2536b7c5d0629093ad886e10ac05f3623")
+
+    if is_plat("linux") then
+        add_syslinks("pthread")
+    end
+
+    on_install(function (package)
+        os.cp("pocketfft_hdronly.h", package:installdir("include"))
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            #include <pocketfft_hdronly.h>
+            void test() {
+                pocketfft::shape_t var;
+            }
+        ]]}, {configs = {languages = "c++11"}}))
+    end)