Update some URLs

Author: alexcrichton

libm/README.md

@@ -12,9 +12,9 @@ The short term goal of this library is to [enable math support (e.g. `sin`, `ata
 `wasm32-unknown-unknown` target][wasm] (cf. [rust-lang-nursery/compiler-builtins][pr]). The longer
 term goal is to enable [math support in the `core` crate][core].
 
-[wasm]: https://github.com/japaric/libm/milestone/1
+[wasm]: https://github.com/rust-lang-nursery/libm/milestone/1
 [pr]: https://github.com/rust-lang-nursery/compiler-builtins/pull/248
-[core]: https://github.com/japaric/libm/milestone/2
+[core]: https://github.com/rust-lang-nursery/libm/milestone/2
 
 ## Already usable