Update ui tests to 2018 edition

test_suite/tests/ui/unexpected-literal/container.rs

@@ -1,5 +1,4 @@
-#[macro_use]
-extern crate serde_derive;
+use serde_derive::Serialize;
 
 #[derive(Serialize)]
 #[serde("literal")]

test_suite/tests/ui/unexpected-literal/container.stderr

@@ -1,7 +1,7 @@
 error: unexpected literal in serde container attribute
- --> $DIR/container.rs:5:9
+ --> $DIR/container.rs:4:9
   |
-5 | #[serde("literal")]
+4 | #[serde("literal")]
   |         ^^^^^^^^^
 
 error: aborting due to previous error

test_suite/tests/ui/unexpected-literal/field.rs

@@ -1,5 +1,4 @@
-#[macro_use]
-extern crate serde_derive;
+use serde_derive::Serialize;
 
 #[derive(Serialize)]
 struct S {

test_suite/tests/ui/unexpected-literal/field.stderr

@@ -1,7 +1,7 @@
 error: unexpected literal in serde field attribute
- --> $DIR/field.rs:6:13
+ --> $DIR/field.rs:5:13
   |
-6 |     #[serde("literal")]
+5 |     #[serde("literal")]
   |             ^^^^^^^^^
 
 error: aborting due to previous error

test_suite/tests/ui/unexpected-literal/variant.rs

@@ -1,5 +1,4 @@
-#[macro_use]
-extern crate serde_derive;
+use serde_derive::Serialize;
 
 #[derive(Serialize)]
 enum E {

test_suite/tests/ui/unexpected-literal/variant.stderr

@@ -1,7 +1,7 @@
 error: unexpected literal in serde variant attribute
- --> $DIR/variant.rs:6:13
+ --> $DIR/variant.rs:5:13
   |
-6 |     #[serde("literal")]
+5 |     #[serde("literal")]
   |             ^^^^^^^^^
 
 error: aborting due to previous error