== build on DragonFly guest (dfbsd-maxx@dfbsd, cc 8.3) ==
$ cc -O2 -Wall -o pick_crtcs_model pick_crtcs_model.c
build: no warnings, exit 0

== note: first model revision looped N to 15; the 15-connector run
== (5^15 = 30,517,578,125 calls) outran the 120s ssh command timeout,
== which is itself a demonstration of the blowup (guest stayed up).