Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch

llvm-svn: 146960
diff --git a/llvm/lib/CodeGen/ScheduleDAG.cpp b/llvm/lib/CodeGen/ScheduleDAG.cpp
index 1e9b5c8..e829668 100644
--- a/llvm/lib/CodeGen/ScheduleDAG.cpp
+++ b/llvm/lib/CodeGen/ScheduleDAG.cpp
@@ -31,6 +31,8 @@
   cl::desc("Stress test instruction scheduling"));
 #endif
 
+void SchedulingPriorityQueue::anchor() { }
+
 ScheduleDAG::ScheduleDAG(MachineFunction &mf)
   : TM(mf.getTarget()),
     TII(TM.getInstrInfo()),