Update miri links

Miri has been moved to `rust-lang` a couple of days ago.

Author: phansch

CONTRIBUTING.md

@@ -162,7 +162,7 @@ it can be found [here][rctd].
 Currently building Rust will also build the following external projects:
 
 * [clippy](https://github.com/rust-lang-nursery/rust-clippy)
-* [miri](https://github.com/solson/miri)
+* [miri](https://github.com/rust-lang/miri)
 * [rustfmt](https://github.com/rust-lang-nursery/rustfmt)
 * [rls](https://github.com/rust-lang-nursery/rls/)
 

src/tools/publish_toolstate.py

@@ -25,7 +25,7 @@
 }
 
 REPOS = {
-    'miri': 'https://github.com/solson/miri',
+    'miri': 'https://github.com/rust-lang/miri',
     'clippy-driver': 'https://github.com/rust-lang/rust-clippy',
     'rls': 'https://github.com/rust-lang/rls',
     'rustfmt': 'https://github.com/rust-lang/rustfmt',