Fix typo in rmake.rs

Author: NobodyXu

tests/run-make/broken-pipe-no-ice/rmake.rs

@@ -11,7 +11,7 @@
 // Internal Compiler Error strangely, but it doesn't even go through normal diagnostic infra. Very
 // strange.
 
-#![feature(anonymous_pipe)
+#![feature(anonymous_pipe)]
 
 use std::io::Read;
 use std::process::{Command, Stdio};