Reduce warnings

src/header/unistd/getopt.rs

@@ -2,7 +2,7 @@
 
 use core::ptr;
 
-use header::{getopt, stdio, string};
+use header::getopt;
 use platform::types::*;
 
 #[allow(non_upper_case_globals)]

src/header/unistd/mod.rs

@@ -3,7 +3,7 @@
 use core::{ptr, slice};
 
 use c_str::CStr;
-use header::{limits, sys_time};
+use header::limits;
 use header::time::timespec;
 use platform;
 use platform::types::*;