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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146960 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachinePassRegistry.cpp b/lib/CodeGen/MachinePassRegistry.cpp
index 9f4ef12..58e067b 100644
--- a/lib/CodeGen/MachinePassRegistry.cpp
+++ b/lib/CodeGen/MachinePassRegistry.cpp
@@ -16,6 +16,7 @@
 
 using namespace llvm;
 
+void MachinePassRegistryListener::anchor() { }
 
 /// Add - Adds a function pass to the registration list.
 ///