Well, everyone was right. Although I did not build anything, or install gsl or cblas0, they were messed up. I reinstalled them to no avail, as evidenced by the fact that siril blew up in exactly the same way KStars did while trying to register images. I reinstalled the OS, installed KStars and Siril and all is well. I am not using the bleeding-edge version, but I will tonight.

Thanks to all.