Fix compilation adding constructor for 'incoming_servers_t'

A constructor is required to overcome C++11 limitation of type
no longer being an aggregate due to default member initialization.

include/proxysql_admin.h

@@ -122,6 +122,9 @@ struct incoming_servers_t {
 	SQLite3_result* incoming_group_replication_hostgroups = NULL;
 	SQLite3_result* incoming_galera_hostgroups = NULL;
 	SQLite3_result* incoming_aurora_hostgroups = NULL;
+
+	incoming_servers_t();
+	incoming_servers_t(SQLite3_result*, SQLite3_result*, SQLite3_result*, SQLite3_result*, SQLite3_result*);
 };
 
 class ProxySQL_Admin {

lib/ProxySQL_Admin.cpp

@@ -978,6 +978,22 @@ bool is_admin_command_or_alias(const std::vector<std::string>& cmds, char *query
 	return false;
 }
 
+incoming_servers_t::incoming_servers_t() {}
+
+incoming_servers_t::incoming_servers_t(
+	SQLite3_result* incoming_mysql_servers,
+	SQLite3_result* incoming_replication_hostgroups,
+	SQLite3_result* incoming_group_replication_hostgroups,
+	SQLite3_result* incoming_galera_hostgroups,
+	SQLite3_result* incoming_aurora_hostgroups
+) :
+	incoming_mysql_servers(incoming_mysql_servers),
+	incoming_replication_hostgroups(incoming_replication_hostgroups),
+	incoming_group_replication_hostgroups(incoming_group_replication_hostgroups),
+	incoming_galera_hostgroups(incoming_galera_hostgroups),
+	incoming_aurora_hostgroups(incoming_aurora_hostgroups)
+{}
+
 int ProxySQL_Test___GetDigestTable(bool reset, bool use_swap) {
 	int r = 0;
 	if (!GloQPro) return 0;

lib/ProxySQL_Cluster.cpp

@@ -1424,9 +1424,9 @@ uint64_t compute_servers_tables_raw_checksum(const vector<MYSQL_RES*>& results)
 
 incoming_servers_t convert_servers_resultsets(const std::vector<MYSQL_RES*>& results) {
 	if (results.size() != sizeof(incoming_servers_t) / sizeof(void*)) {
-		return {};
+		return incoming_servers_t {};
 	} else {
-		return {
+		return incoming_servers_t {
 			get_SQLite3_resulset(results[0]).release(),
 			get_SQLite3_resulset(results[1]).release(),
 			get_SQLite3_resulset(results[2]).release(),