optimize lang config to fix issue on windows

Author: Sunrisepeak

config.xlings

@@ -26,4 +26,8 @@ d2x = {
     },
 }
 
---xlings_llm_config = "llm.config.xlings"
+--xlings_llm_config = "llm.config.xlings"
+
+mcpp = {
+    lang = "en", -- option: en, zh
+}

dslings/xmake.lua

@@ -1,12 +1,8 @@
-local dslings_dir = os.scriptdir()
-
-includes(path.join(dslings_dir, "d2x/common.lua"))
-
 if is_host("windows") then
     set_encodings("source:utf-8", "target:utf-8")
 end
 
-if get_local_lang() == "zh" then
+if mcpp.lang == "zh" then
     add_includedirs(".")
 
     target("00-0-hello-mcpp")