Switch to purely namespaced enums

This breaks code that referred to variant names in the same namespace as
their enum. Reexport the variants in the old location or alter code to
refer to the new locations:

```
pub enum Foo {
    A,
    B
}

fn main() {
    let a = A;
}
```
=>
```
pub use self::Foo::{A, B};

pub enum Foo {
    A,
    B
}

fn main() {
    let a = A;
}
```
or
```
pub enum Foo {
    A,
    B
}

fn main() {
    let a = Foo::A;
}
```

[breaking-change]

1 files changed, 2 insertions, 0 deletions

diff --git a/src/liblibc/lib.rs b/src/liblibc/lib.rs
index 6756d4b21ff..1a86ef2c6e0 100644
--- a/src/liblibc/lib.rs
+++ b/src/liblibc/lib.rs
@@ -85,6 +85,8 @@ extern crate core;
 #[cfg(test)] extern crate test;
 #[cfg(test)] extern crate native;
 
+pub use self::Nullable::*;
+
 // Explicit export lists for the intersection (provided here) mean that
 // you can write more-platform-agnostic code if you stick to just these
 // symbols.