Add a virtual dtor to Delegate to silence -Wnon-virtual-dtor

llvm-svn: 127311
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.h b/llvm/lib/CodeGen/LiveRangeEdit.h
index db62eaa..aa86740 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.h
+++ b/llvm/lib/CodeGen/LiveRangeEdit.h
@@ -34,6 +34,7 @@
   struct Delegate {
     /// Called immediately before erasing a dead machine instruction.
     virtual void LRE_WillEraseInstruction(MachineInstr *MI) {}
+    virtual ~Delegate() {}
   };
 
 private: