Make use of new `big_sepM2` in Iris.

1 job for master in 7 minutes and 28 seconds (queued for 2 seconds)
Status Job ID Name Coverage
failed #32192


Name Stage Failure
failed Build
Makefile.coq:317: recipe for target 'all' failed
make[1]: *** [all] Error 2
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2

real 2m21.455s
user 16m16.100s
sys 0m30.004s
ERROR: Job failed: exit code 1