Point at while true span instead of entire block

src/test/ui/codemap_tests/unicode_3.stderr

@@ -2,9 +2,7 @@ warning: denote infinite loops with `loop { ... }`
   --> $DIR/unicode_3.rs:14:45
    |
 14 |     let s = "ZͨA͑ͦ͒͋ͤ͑̚L̄͑͋Ĝͨͥ̿͒̽̈́Oͥ͛ͭ!̏"; while true { break; }
-   |                       ----------^^^^^^^^^^^
-   |                       |
-   |                       help: use `loop`
+   |                       ^^^^^^^^^^ help: use `loop`
    |
    = note: #[warn(while_true)] on by default
 

src/test/ui/issue-1962.stderr

@@ -1,15 +1,8 @@
 error: denote infinite loops with `loop { ... }`
   --> $DIR/issue-1962.rs:14:3
    |
-14 |     while true  { //~ ERROR denote infinite loops with `loop
-   |     ^---------
-   |     |
-   |  ___help: use `loop`
-   | |
-15 | |     i += 1;
-16 | |     if i == 5 { break; }
-17 | |   }
-   | |___^
+14 |   while true  { //~ ERROR denote infinite loops with `loop
+   |   ^^^^^^^^^^ help: use `loop`
    |
    = note: requested on the command line with `-D while-true`
 

src/test/ui/lint/suggestions.stderr

@@ -75,18 +75,8 @@ warning: function is marked #[no_mangle], but not exported
 warning: denote infinite loops with `loop { ... }`
   --> $DIR/suggestions.rs:34:5
    |
-34 |       while true { // should suggest `loop`
-   |       ^---------
-   |       |
-   |  _____help: use `loop`
-   | |
-35 | |     //~^ WARN denote infinite loops
-36 | |         let mut a = (1); // should suggest no `mut`, no parens
-37 | |         //~^ WARN does not need to be mutable
-...  |
-44 | |         println!("{}", a);
-45 | |     }
-   | |_____^
+34 |     while true { // should suggest `loop`
+   |     ^^^^^^^^^^ help: use `loop`
    |
    = note: #[warn(while_true)] on by default