Log Message:
   make "extra files" a fatal error again, based on various feedback.

thanks - btw, my (private) comment that we'd lose libc.so.x.y again was
probably wrong except in the case of old $DESTDIR having the old libc
already....but that would give you a mostly working system anyway..
   
   i'll consider adding an optional switch and associated build infrastructure
   to enable the "non fatal extra files" functionality instead.

i think having the ability to ignore set lists failures *is* a good
idea, it's just a dangerous default...


.mrg.