bug#73289: ceph 17.2.5 no longer installable

[Yann Dupont <Yann.Dupont@univ-nantes.fr>]

Hello everyone,
ceph is no longer installable, probably since the core update.

see https://ci.guix.gnu.org/build/5775507/log

The main reason seems to be the boost update. A relatively simple fix 
exists for recent versions of ceph , (see 
https://github.com/ceph/ceph/commit/244c5ebbd4d5683da7f57612cc02e946aae7fd73) 
but this has not been backported to older versions of ceph.

Adding this patch to ceph 17.2.5 works. We have several options:

-> stay in 17.2.5, add this patch, which is little work and not a big risk
-> take the opportunity to upgrade to 17.2.7 (which is currently the 
last stable version of the 17.2 series), I've tested it and it *seems* 
to work,
-> take the opportunity to upgrade to a more recent version of ceph (18 
or 19), but that's a whole other job.

What do you think?

I'll post the patch to at least correct the compilation and upgrade to 
17.2.7