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

llvm-svn: 146960
diff --git a/llvm/lib/CodeGen/MachinePassRegistry.cpp b/llvm/lib/CodeGen/MachinePassRegistry.cpp
index 9f4ef12..58e067b 100644
--- a/llvm/lib/CodeGen/MachinePassRegistry.cpp
+++ b/llvm/lib/CodeGen/MachinePassRegistry.cpp
@@ -16,6 +16,7 @@
 
 using namespace llvm;
 
+void MachinePassRegistryListener::anchor() { }
 
 /// Add - Adds a function pass to the registration list.
 ///