Auto merge of #4619 - camjackson:patch-1, r=alexcrichton
authorbors <bors@rust-lang.org>
Sun, 15 Oct 2017 17:00:09 +0000 (17:00 +0000)
committerbors <bors@rust-lang.org>
Sun, 15 Oct 2017 17:00:09 +0000 (17:00 +0000)
Document how to make `build.rs` write to the terminal

Documenting the solution mentioned here: https://github.com/rust-lang/cargo/issues/985


Trivial merge