configure scripts became ubiquitous in the mid nineties about the same time as Linux.

Prior to that, it was FTP-uncompress-untar-edit config.h-make.

You'd be expected to spend 10-30 minutes scanning a long config.h file or similar and adjusting as per your local unix variant. Often a BSD or SVR4 like system (rarely both) would work mostly out of the box. AIX, Ultrix, or HP-UX were more troublesome from what I can remember, SunOS or Solaris (never both ;-)) would mostly work out of the box as that was commonly the dev platform.