Bump std++.

6 jobs for master in 15 minutes and 53 seconds
Status Job ID Name Coverage
  Build
passed #46640
fp
build-coq.8.10.0

00:09:20

passed #46639
fp
build-coq.8.10.1

00:09:25

passed #46643
fp
build-coq.8.8.2

00:06:41

passed #46642
fp-timing
build-coq.8.9.0

00:07:12

passed #46641
fp
build-coq.8.9.1

00:08:31

passed #46638
fp
build-coq.dev

00:15:53