update Makefile

1 job for master in 11 minutes and 37 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #24847
fp
build-iris.dev

00:11:37

 
Name Stage Failure
failed
build-iris.dev 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 5m19.155s
user 26m18.008s
sys 0m38.676s
ERROR: Job failed: exit code 1