fail obligations that depend on erroring obligations

Fix a bug where an obligation that depend on an erroring obligation would
be regarded as successful, leading to global cache pollution and random
lossage.

Fixes #33723.
Fixes #34503.

src/test/run-pass/issue-34503.rs

@@ -0,0 +1,20 @@
+// Copyright 2016 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() {
+    struct X;
+    trait Foo<T> {
+        fn foo(&self) where (T, Option<T>): Ord {}
+        fn bar(&self, x: &Option<T>) -> bool
+        where Option<T>: Ord { *x < *x }
+    }
+    impl Foo<X> for () {}
+    let _ = &() as &Foo<X>;
+}