al_rebase_path - Allegro 5 API
bool al_rebase_path(const ALLEGRO_PATH *head, ALLEGRO_PATH *tail)
Concatenate two path structures, modifying the second path structure. If
tail is an absolute path, this function does nothing. Otherwise, the
drive and path components in head are inserted at the start of
For example, if head is “/anchor/” and
tail is “data/file.ext”, then after the call
tail becomes “/anchor/data/file.ext”.