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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146959 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/LiveVariables.cpp b/lib/Analysis/LiveVariables.cpp
index 3a32500..ff6607d 100644
--- a/lib/Analysis/LiveVariables.cpp
+++ b/lib/Analysis/LiveVariables.cpp
@@ -143,6 +143,8 @@
   }
 }
 
+void LiveVariables::Observer::anchor() { }
+
 LiveVariables::LivenessValues
 LiveVariablesImpl::merge(LiveVariables::LivenessValues valsA,
                          LiveVariables::LivenessValues valsB) {