Minor changes to Equiv/Biinv and files that use it #1534

Job	Run time
nix	4m 4s
quick-build (supported, ubuntu-latest)	3m 44s
quick-build (latest, ubuntu-latest)	3m 30s
quick-build (dev, ubuntu-latest)	3m 33s
opam-build (supported, ubuntu-latest)	7m 13s
opam-build (8.17, ubuntu-latest)	5m 43s
opam-build (latest, ubuntu-latest)	5m 23s
opam-build (dev, ubuntu-latest)	5m 41s
build (supported)	5m 28s
build (latest)	5m 10s
build (dev, --warnings)	4m 28s
doc-timing	1m 48s
doc-coqdoc	1m 23s
doc-alectryon	15m 26s
doc-dep-graphs	11m 45s
coqchk (supported)	1m 57s
coqchk (latest)	2m 22s
coqchk (dev)	1m 52s
install (supported)	1m 26s
install (latest)	1m 26s
install (dev)	1m 52s
deploy-doc	0s
delete-artifacts	3s
	1h 35m 17s

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