compatibility with coq-interval.4.11

[andrew-appel]

It's possible, as discussed here, that vcfloat is not compatible with coq-interval.4.11.

Check this, and if so:

1. Add upper bounds (regarding coq-interval) to opam files of all releases of vcfloat in the archive;
2. Make the master branch of vcfloat compatible with coq-interval.4.11 and then create a new opam release.

[andrew-appel]

Most likely, vcfloat.2.2 (and master) is just fine, it might just have been vcfloat.2.1.1 that needed the upper bound:
coq/opam#3122

[andrew-appel]

Never mind, this only affected vcfloat.2.1.1 and it has been corrected by adjusting the opam file of that release.