remove either dependency we are not using

Author: nikomatsakis

src/Cargo.lock

@@ -1781,7 +1781,6 @@ dependencies = [
  "bitflags 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "chalk-engine 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "fmt_macros 0.0.0",
  "graphviz 0.0.0",

src/librustc/Cargo.toml

@@ -11,7 +11,6 @@ crate-type = ["dylib"]
 [dependencies]
 arena = { path = "../libarena" }
 bitflags = "1.0"
-either = "1.5.0"
 fmt_macros = { path = "../libfmt_macros" }
 graphviz = { path = "../libgraphviz" }
 jobserver = "0.1"

src/librustc/lib.rs

@@ -79,7 +79,6 @@
 extern crate arena;
 #[macro_use] extern crate bitflags;
 extern crate core;
-extern crate either;
 extern crate fmt_macros;
 extern crate getopts;
 extern crate graphviz;