[ThinLTO] Add code comment. NFC

llvm-svn: 375500

llvm/lib/Transforms/IPO/FunctionImport.cpp

@@ -952,6 +952,9 @@ void llvm::thinLTOResolvePrevailingInModule(
     if (NewLinkage == GV.getLinkage())
       return;
     if (GlobalValue::isLocalLinkage(GV.getLinkage()) ||
+        // Don't internalize anything here, because the code below
+        // lacks necessary correctness checks. Leave this job to
+        // LLVM 'internalize' pass.
         GlobalValue::isLocalLinkage(NewLinkage) ||
         // In case it was dead and already converted to declaration.
         GV.isDeclaration())