support windows ffi.lib

Author: elipmoc

Diff for: build.rs

@@ -1,3 +1,5 @@
 fn main() {
-    println!("cargo:rustc-link-lib=dylib=ffi");
+    if cfg!(not(target_os = "windows")) {
+        println!("cargo:rustc-link-lib=dylib=ffi");
+    }
 }