Add missing gcc 6 include
#include <vespa/searchlib/common/transport.h>
#include <vespa/searchlib/common/hitrank.h>
#include <vespa/fastos/timestamp.h>
+#include <vector>
-namespace search
-{
+namespace search {
+
+namespace fs4transport {
-namespace fs4transport
-{
using vespalib::string;
enum fnet_feature_masks {
