fix compilation error / clang warnings

lib/query/mu-xapian.cc

@@ -79,7 +79,7 @@ xapian_query_value (const Mu::Tree& tree)
 		return make_query(v, parts.front(), true/*maybe-wildcard*/);
 
 	std::vector<Xapian::Query> phvec;
-	for (const auto p: parts)
+	for (const auto& p: parts)
 		phvec.emplace_back(make_query(v, p, false/*no wildcards*/));
 
         return Xapian::Query (Xapian::Query::OP_PHRASE, phvec.begin(), phvec.end());

lib/query/test-tokenizer.cc

@@ -133,7 +133,7 @@ static void
 test_to_string ()
 {
 	std::stringstream ss;
-	for (const auto t: tokenize ("foo and bar xor not cuux or fnorb"))
+	for (auto&& t: tokenize ("foo and bar xor not cuux or fnorb"))
 		ss << t << ' ';
 
 	g_assert_true (ss.str() ==