libstd: add missing imports

src/libstd/dynamic_lib.rs

@@ -290,6 +290,7 @@ pub mod dl {
     use c_str::ToCStr;
     use iter::IteratorExt;
     use libc;
+    use ops::FnOnce;
     use os;
     use ptr;
     use result::Result;

src/libstd/os.rs

@@ -163,6 +163,7 @@ pub fn getcwd() -> IoResult<Path> {
 pub mod windoze {
     use libc::types::os::arch::extra::DWORD;
     use libc;
+    use ops::FnMut;
     use option::Option;
     use option::Option::None;
     use option;