修复rustc 1.54引入的cargo:rustc-link-arg-*编译指令检查

rust-lang/cargo#9523

Author: gaoqiangz

build.rs

@@ -16,11 +16,13 @@ fn main() {
 
     cfg.compile("pbx");
 
+    #[cfg(target = "cdylib")]
     build_def();
 }
 
 //生成导出符号定义文件
 //解决rust msvc 32bit dll编译符号被截断的问题
+#[cfg(target = "cdylib")]
 fn build_def() {
     use std::{fs::OpenOptions, io::Write, path::PathBuf};