Work around breaking change in libc crate

The libc crate started using the #[deprecated] attribute, which is not
supported on Rust 1.8.0 stable, and results in a compile error. This
change was presumably introduced in commit 13ce9f8 [1] as part of pull
request 859 [2].

The solution is to put Cargo.lock under source control and freeze all
dependency versions, to be more resilient to external changes.

[1]: rust-lang/libc@13ce9f8
[2]: rust-lang/libc#859

Author: ruuda

.gitignore

@@ -1,6 +1,5 @@
 # Cargo files
 /target
-/Cargo.lock
 
 # Editor files
 *.swp