Of course you can't guarantee that the library will get installed to the directory you think it'll get installed to, since there's no unified installer system f

Of course you can't guarantee that the library will get installed to the directory you think it'll get installed to, since there's no unified installer system for all Linux distributions. So even a relative path doesn't necessarily work. The best you can do is hope that the Freedesktop filesystem hierarchy is being followed, but that forces installing software for all users at once instead of per user, despite Linux supposedly being a multiuser OS.