proot-static build failures (master and core-updates)

[Greg Hogan]

We now have a build attempt on Cuirass:
https://ci.guix.gnu.org/build/982993/details

proot-static is required for building relocatable packages.

That is on core-updates, but I see the same issue building from source
on master, as well as running manually outside of the proot. The check
fails on timeout, but test-25069c12 and test-25069c13 are trivial and
I can see no reason why these test processes do not terminate
immediately rather than execve continually.

Greg