Fix linkage of mismatched weak globals.  This unbreaks 300.twolf

llvm-svn: 18494
diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp
index c5d1240..d58acbe 100644
--- a/llvm/lib/Linker/LinkModules.cpp
+++ b/llvm/lib/Linker/LinkModules.cpp
@@ -531,6 +531,8 @@
           else
             DGV->setConstant(true);
         }
+        SGV->setLinkage(GlobalValue::ExternalLinkage);
+        SGV->setInitializer(0);
       }
 
       ValueMap.insert(std::make_pair(SGV,