uucp and uri take an awful lot of RAM to build on 5.0.0+tsan

[OlivierNicole]

Reported by @ElectreAAS.

To reproduce:

git clone git@github.com:ElectreAAS/irmin.git
cd irmin
git checkout direct-style
opam switch create . 5.0.0+tsan --no-install
opam pin -n . --with-version=dev --kind=path
opam install ./irmin-pack --deps-only --with-test -j1

(Using the direct-style branch is probably not necessary.)

Without -j1 the install causes OOM: when building uucp, ocamlopt.opt peaks at 16 GB of memory, and similarly with uri.

To do

• Check whether this still happens on the current working version of TSan
• Investigate the causes of this memory consumption