Use the correct span for out-of-range int literals.

This corrects the error message to point at the literal, not the next
token.

Closes #17123.

src/test/compile-fail/int-literal-too-large-span.rs

@@ -0,0 +1,17 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// issue #17123
+
+fn main() {
+    100000000000000000000000000000000 //~ ERROR int literal is too large
+
+        ; // the span shouldn't point to this.
+}