Add a test file for distinct ty_native types

This should have gone into patch
77f5d14f14630da997f13de28ea86e8320957180, had I not forgotten to add
the file.

src/test/compile-fail/native-type-mismatch.rs

@@ -0,0 +1,7 @@
+// error-pattern:expected native but found native
+use std;
+
+fn main() {
+    let std::os::libc::FILE f = std::io::rustrt::rust_get_stdin();
+    std::os::libc::opendir(f);
+}