[Bug libstdc++/69331] FAIL: 20_util/shared_ptr/thread/default_weaktoshared.cc execution test

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69331

--- Comment #22 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think we can rely on the relative placement, but it would be better to add
that to the _l flags used for the testsuite.