Rebased and replaced yield with deschedule

src/libstd/task/mod.rs

@@ -680,7 +680,7 @@ fn test_rekillable_not_nested() {
         // receiving anything since
         // this block should be nested
         // into a unkillable block.
-        yield();
+        deschedule();
     }
 }
 

src/llvm

@@ -1 +1 @@
-Subproject commit f67442eee27d3d075a65cf7f9a70f7ec6649ffd1
+Subproject commit 0964c68ddf2c67ce455e7443a06f4bb3db9e92bb