Add resultset helper function to mariadb_func.h

Added a function that converts resultsets into matrices of strings.

maxscale-system-test/mariadb_func.h

@@ -27,6 +27,7 @@
 #include <vector>
 
 typedef std::vector<std::string> Row;
+typedef std::vector<Row> Result;
 
 /**
  * Opens connection to DB: wropper over mysql_real_connect
@@ -215,7 +216,17 @@ int find_field(MYSQL* conn, const char* sql, const char* field_name, char* value
  *
  * @return The first row as a list of strings
  */
-std::vector<std::string> get_row(MYSQL* conn, std::string sql);
+Row get_row(MYSQL* conn, std::string sql);
+
+/**
+ * Execute a query and return the result
+ *
+ * @param conn The connection to use
+ * @param sql  The query to execute
+ *
+ * @return The result as a list of rows
+ */
+Result get_result(MYSQL* conn, std::string sql);
 
 int get_int_version(std::string version);