In QueryLoggingSolver call flush() on std::ofstream so that queries

get correctly logged if an assertion failure is hit later on.

lib/Solver/QueryLoggingSolver.cpp

@@ -74,6 +74,7 @@ void QueryLoggingSolver::flushBuffer() {
               // we do additional check here to log only timeouts in case
               // user specified negative value for minQueryTimeToLog param
               os << logBuffer.str();              
+              os.flush();
           }                    
       }