Fix build with glibc 2.27

diff --git a/components/assist_ranker/ranker_example_util.cc b/components/assist_ranker/ranker_example_util.cc
index 54d4dbd..ceedd8f 100644
--- a/components/assist_ranker/ranker_example_util.cc
+++ b/components/assist_ranker/ranker_example_util.cc
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <cmath>
+
 #include "components/assist_ranker/ranker_example_util.h"
 #include "base/bit_cast.h"
 #include "base/format_macros.h"