Fix unintentional use of operator bool.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155978 91177308-0d34-0410-b5e6-96231b3b80d8

tools/bugpoint/ToolRunner.cpp

@@ -128,7 +128,7 @@ static int RunProgramRemotelyWithTimeout(const sys::Path &RemoteClientPath,
       ErrorFile.close();
     }
 
-    errs() << OS;
+    errs() << OS.str();
   }
 
   return ReturnCode;