update build system and Iris

.gitlab-ci.yml

Makefile

build/opam-ci.sh

build/opam-pins.sh

opam

opam.pins

theories/adequacy.v

theories/base/at_shared.v

theories/base/fork.v

theories/base/ghosts.v

theories/base/helpers.v

theories/base/na_shared.v

theories/blocks.v

theories/examples/nat_tokens.v

theories/examples/rcu.v

theories/examples/rcu_data.v

theories/examples/ticket_lock.v

theories/gps/cas.v

theories/gps/fai.v

theories/gps/write.v