Apply a patch from Nathan Keynes, which speeds up llvm-link on

the testcases in PR1860 from taking more than 1 hour (when I killed it)
to taking 1s.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52347 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Linker/LinkModules.cpp

@@ -156,7 +156,6 @@ static bool RecursiveResolveTypesI(const PATypeHolder &DestTy,
       RecursiveResolveTypesI(cast<PointerType>(DestTy.get())->getElementType(),
                              cast<PointerType>(SrcTy.get())->getElementType(),
                              Pointers);
-    Pointers.pop_back();
     return Result;
   }
   }