[Bug d/89254] std.net.curl and std.parallelism unittests hang

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89254

--- Comment #1 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
I don't think you should be seeing a thread deadlock in std.net.curl after
r268746.

I've not been able to reproduce the never timing out part.  The process has
always been killed after 600 seconds.