MXS-1503: Test that no extra slaves are taken into use

Added a test that verifies that the slave connection count restrictions
work.

maxscale-system-test/mariadb_func.h

@@ -24,6 +24,7 @@
 #include <stdarg.h>
 #include <errno.h>
 #include <string>
+#include <vector>
 
 /**
  * Opens connection to DB: wropper over mysql_real_connect
@@ -204,6 +205,16 @@ int get_conn_num(MYSQL* conn, std::string ip, std::string hostname, std::string
  */
 int find_field(MYSQL* conn, const char* sql, const char* field_name, char* value);
 
+/**
+ * Execute a query and return the first row
+ *
+ * @param conn The connection to use
+ * @param sql  The query to execute
+ *
+ * @return The first row as a list of strings
+ */
+std::vector<std::string> get_row(MYSQL* conn, std::string sql);
+
 int get_int_version(std::string version);
 
 #endif // MARIADB_FUNC_H