Temporarily ignoring tests that can go into infinite loops.

src/libcore/arc.rs

@@ -206,6 +206,7 @@ mod tests {
     }
 
     #[test]
+    #[ignore] // this can probably infinite loop too.
     fn exclusive_arc() {
         let mut futures = [];
 

src/libcore/sys.rs

@@ -173,6 +173,7 @@ mod tests {
     }
 
     #[test]
+    #[ignore] // this can go into infinite loops
     fn condition_variable() {
         let lock = arc::arc(create_lock());
         let lock2 = arc::clone(&lock);