Un-xfail two tests under check-fast

Closes #937. Fixed by majick.

src/test/run-pass/linked-failure.rs

@@ -1,5 +1,4 @@
 // -*- rust -*-
-// xfail-fast
 // error-pattern:1 == 2
 use std;
 import std::task;

src/test/run-pass/lots-a-fail.rs

@@ -1,5 +1,4 @@
 // FIXME: Importing std::task doesn't work under check-fast?!
-// xfail-fast
 use std;
 import std::task;
 import std::comm;