Utilize fewer reexports

In regards to:

https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729

This commit:

* Changes the #deriving code so that it generates code that utilizes fewer
  reexports (in particur Option::* and Result::*), which is necessary to
  remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized

src/libstd/rt/util.rs

@@ -9,7 +9,8 @@
 // except according to those terms.
 
 use libc::uintptr_t;
-use option::{Some, None, Option};
+use option::Option;
+use option::Option::{Some, None};
 use os;
 use str::{FromStr, from_str, Str};
 use sync::atomic;