Suggest 'a when given a only when appropriate

When encountering a name `a` that isn't resolved, but a label `'a` is
found in the current ribs, only suggest `'a` if this name is the value
expression of a `break` statement.

Solve FIXME.

compiler/rustc_resolve/src/late.rs

@@ -2266,6 +2266,12 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 visit::walk_expr(self, expr);
             }
 
+            ExprKind::Break(None, Some(ref e)) => {
+                // We use this instead of `visit::walk_expr` to keep the parent expr around for
+                // better
+                self.resolve_expr(e, Some(&expr));
+            }
+
             ExprKind::Let(ref pat, ref scrutinee) => {
                 self.visit_expr(scrutinee);
                 self.resolve_pattern_top(pat, PatternSource::Let);