Fix ui test errors

Author: canndrew

src/test/ui/feature-gate-exhaustive-patterns.stderr

@@ -1,7 +1,7 @@
 error[E0005]: refutable pattern in local binding: `Err(_)` not covered
   --> $DIR/feature-gate-exhaustive-patterns.rs:16:9
    |
-16 |     let Ok(_x) = foo(); //~ ERROR refutable pattern in local binding
+LL |     let Ok(_x) = foo(); //~ ERROR refutable pattern in local binding
    |         ^^^^^^ pattern `Err(_)` not covered
 
 error: aborting due to previous error

src/test/ui/reachable/expr_unary.stderr

@@ -1,7 +1,7 @@
 error[E0600]: cannot apply unary operator `!` to type `!`
   --> $DIR/expr_unary.rs:17:16
    |
-17 |     let x: ! = ! { return; }; //~ ERROR unreachable
+LL |     let x: ! = ! { return; }; //~ ERROR unreachable
    |                ^^^^^^^^^^^^^
 
 error: unreachable expression