Runtime interface takes type info by copy

[ahueck]

This should probably be passed by const pointer:

typeart_status typeart_get_containing_type(typeart_type_info type_info, typeart_base_type_info* containing_type,
                                           size_t* byte_offset);

->

typeart_status typeart_get_containing_type(const typeart_type_info* type_info, typeart_base_type_info* containing_type,
                                           size_t* byte_offset);