auto merge of #5118 : youknowone/rust/match-guard, r=nikomatsakis

Fix ICE while there is no remained arms after checking guards.

This fix #3601 also.

src/test/compile-fail/match-non-exhaustive.rs

@@ -0,0 +1,14 @@
+// Copyright 2013 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() {
+    match 0 { 1 => () } //~ ERROR non-exhaustive patterns
+    match 0 { 0 if false => () } //~ ERROR non-exhaustive patterns
+}