Change std inject attributes to outer attributes

The #[phase(syntax,link)] attribute on `extern crate std` needs to be an
outer attribute so it can pretty-print properly.

Also add `#![no_std]` and `#[feature(phase)]` so compiling the
pretty-printed source will work.
auto merge of #14320 : kballard/rust/fix_stdlib_inject_attrs, r=alexcrichton

The #[phase(syntax,link)] attribute on `extern crate std` needs to be an
outer attribute so it can pretty-print properly.

Also add `#![no_std]` and `#[feature(phase)]` so compiling the
pretty-printed source will work.