One more try at fixing the segfaults due to erased iterators

tools/dcdbquery/query.cpp

@@ -399,6 +399,8 @@ void DCDBQuery::execute() {
     auto q = queries.begin();
     while (q != queries.end()) {
 	if (q->first.name != prevSensorName) {
+	    prevSensorName = q->first.name;
+
 	    // Find all queries for the same sensor
 	    std::pair<queryMap_t::iterator, queryMap_t::iterator> range = queries.equal_range(q->first);
 	    
@@ -444,9 +446,6 @@ void DCDBQuery::execute() {
 		genOutput(results, range.first, range.second);
 		results.clear();
 	    }
-
-
-	    prevSensorName = q->first.name;
 	}
 	if (q != queries.end()) {
 	    q++;