servo: Merge #14594 - Upgrade to cargo 0.16.0-nightly (16f38c1 2016-12-14) (from servo:cargoup); r=jdm

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This version includes the new `cargo check`:
rust-lang/cargo#3296

Source-Repo: https://github.com/servo/servo
Source-Revision: be896712ac56f69d95b31e0d5a459fbd86f71bd8

Author: SimonSapin

servo/cargo-commit-hash

@@ -1 +1 @@
-5e3221eac240f1e2c719524ea3c15fde9329dec2
+16f38c1102bddc8e6b6a4322ae41489b769884dc