Update ui tests to 2018 edition

test_suite/tests/ui/precondition/deserialize_dst.stderr

@@ -1,10 +1,10 @@
 error: cannot deserialize a dynamically sized struct
- --> $DIR/deserialize_dst.rs:5:1
+ --> $DIR/deserialize_dst.rs:4:1
   |
-5 | / struct S {
-6 | |     string: String,
-7 | |     slice: [u8],
-8 | | }
+4 | / struct S {
+5 | |     string: String,
+6 | |     slice: [u8],
+7 | | }
   | |_^
 
 error: aborting due to previous error