Fix and enable libstd building

example/std_example.rs

@@ -0,0 +1,9 @@
+use std::io::Write;
+
+fn main() {
+    let _ = ::std::iter::repeat('a' as u8).take(10).collect::<Vec<_>>();
+    let stderr = ::std::io::stderr();
+    let mut stderr = stderr.lock();
+
+    writeln!(stderr, "some {} text", "<unknown>").unwrap();
+}