csearch::get_item_attrs() seems to always be blank for const items

[tomjakubowski]

This prevents rustdoc from inlining docs from another crate's constant items.

example code:

// foo.rs
#![crate_type="lib"]
/// Docs for a const
pub const FOO: &'static str = "Foo bar";

// bar.rs
#![crate_type="lib"]
extern crate foo;

pub use foo::FOO;

(This issue is unrelated to the myriad issues rustdoc currently has with constants, and came up while I was fixing them).

[alexcrichton]

I think we're missing a call to encode_attributes here