Add tests for error message for pattern matching typo

src/test/ui/did_you_mean/multiple-pattern-typo.rs

+// Copyright 2018 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.
+
+fn main() {
+    let x = 3;
+    match x {
+        1 | 2 || 3 => (), //~ ERROR unexpected token `||` after pattern
+        _ => (),
+    }
+}

src/test/ui/did_you_mean/multiple-pattern-typo.stderr

+error: unexpected token `||` after pattern
+  --> $DIR/multiple-pattern-typo.rs:14:15
+   |
+14 |         1 | 2 || 3 => (), //~ ERROR unexpected token `||` after pattern
+   |               ^^
+   |
+   = help: did you mean to use `|` to specify multiple patterns?
+
+error: aborting due to previous error
+