Reapply: "the cargo feature: edition 2018 is stabilized in current nightly"

flip1995 · flip1995 · commit 582ab5a0d074 · 2018-09-14T13:43:20.000+02:00
This reapplies commit 404a09d. Cargo got bumped in rust-lang/rust#54210
diff --git a/Cargo.toml b/Cargo.toml
@@ -1,5 +1,3 @@
-cargo-features = ["edition"]
-
 [package]
 name = "clippy"
 version = "0.0.212"
diff --git a/clippy_lints/Cargo.toml b/clippy_lints/Cargo.toml
@@ -1,5 +1,3 @@
-cargo-features = ["edition"]
-
 [package]
 name = "clippy_lints"
 # begin automatic update
diff --git a/rustc_tools_util/Cargo.toml b/rustc_tools_util/Cargo.toml
@@ -1,5 +1,3 @@
-cargo-features = ["edition"]
-
 [package]
 name = "rustc_tools_util"
 version = "0.1.0"
