add on_load to mbedtls

packages/m/mbedtls/xmake.lua

@@ -12,10 +12,13 @@ package("mbedtls")
         add_deps("cmake")
     end
 
+    on_load(function (package)
+        package:addvar("links", "mbedcrypto", "mbedx509", "mbedtls")
+    end)
+
     if is_plat("windows") and winos.version():gt("winxp") then
         on_install("windows", function (package)
             import("package.tools.cmake").install(package)
-            package:addvar("links", "mbedcrypto", "mbedx509", "mbedtls")
         end)
     end
 
@@ -23,6 +26,5 @@ package("mbedtls")
         io.gsub("./Makefile", "DESTDIR=/usr/local", "DESTDIR=" .. package:installdir())
         os.vrun("make")
         os.vrun("make install")
-        package:addvar("links", "mbedcrypto", "mbedx509", "mbedtls")
     end)