Update rand version

Author: JohnTitor

Cargo.lock

@@ -2747,7 +2747,7 @@ version = "0.0.0"
 dependencies = [
  "graphviz 0.0.0",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_fs_util 0.0.0",

src/librustc_incremental/Cargo.toml

@@ -12,7 +12,7 @@ crate-type = ["dylib"]
 [dependencies]
 graphviz = { path = "../libgraphviz" }
 log = "0.4"
-rand = "0.5"
+rand = "0.6"
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 serialize = { path = "../libserialize" }