Add libsodium (#112)

* Libsodium attempt #1

* Ensure static linking is done correctly

* Review changes

* Attempt to fix linker errors

* Fix arch

* Why is this not unified tho

packages/l/libsodium/xmake.lua

@@ -0,0 +1,55 @@
+package("libsodium")
+
+    set_homepage("https://libsodium.org")
+    set_description("Sodium is a new, easy-to-use software library for encryption, decryption, signatures, password hashing and more.")
+
+    if is_plat("windows") then
+        set_urls("https://download.libsodium.org/libsodium/releases/libsodium-$(version)-stable-msvc.zip")
+        add_versions("1.0.18", "5d313795d13fc99fb925c4d49c16f1a80779f69e49b58a9a4260bd3b150d45b7")
+    elseif is_plat("linux", "macosx") then
+        add_deps("autoconf", "automake", "libtool", "pkg-config")
+        set_urls("https://download.libsodium.org/libsodium/releases/libsodium-$(version)-stable.tar.gz")
+        add_versions("1.0.18", "91441b13c965e241cd64bb42823f1f2d882f08f8f40f1716cda17df2b3450af2")
+    elseif is_plat("mingw") then
+        set_urls("https://download.libsodium.org/libsodium/releases/libsodium-$(version)-stable-mingw.tar.gz")
+        add_versions("1.0.18", "d2f1918e198cd86b9e6ba05b2f5c2dc86753875ea3ee887892767231c6b7e121")
+    end
+
+    on_load(function (package)
+        if not package:config("shared") then
+            package:add("defines", "SODIUM_STATIC")
+        end
+    end)
+    
+    on_install("windows", function (package)
+        os.cp("include", package:installdir())
+        os.cp(path.join((package:is_arch("x64") and "x64" or "Win32"), (package:debug() and "Debug" or "Release"), "v142", (package:config("shared") and "dynamic" or "static"), "*"), package:installdir("lib"))
+    end)
+
+    on_install("mingw", function (package)
+
+        local root_dir = (package:is_arch("x86_64") and "libsodium-win64" or "libsodium-win32")
+
+        os.cp(path.join(root_dir, "include"), package:installdir())
+        if package:config("shared") then
+            os.cp(path.join(root_dir, "lib", "libsodium.dll.a"), package:installdir("lib"))
+            os.cp(path.join(root_dir, "bin", "*"), package:installdir("lib"))
+        else
+            os.cp(path.join(root_dir, "lib", "libsodium.a"), package:installdir("lib"))
+        end
+    end)
+
+    on_install("linux", "macosx", function (package)
+        import("package.tools.autoconf").install(package)
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+            int test(int args, char** argv) {
+                if (sodium_init() < 0) {
+                    return -1;
+                }
+                return 0;
+            }
+        ]]}, {includes = "sodium.h"}))
+    end)