[Bug libobjc/63765] [5.0 Regression] libobjc testsuite failures on AIX caused by setting _XOPEN_SOURCE

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63765

--- Comment #6 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot 
Uni-Bielefeld.DE> ---
> --- Comment #5 from David Edelsohn <dje at gcc dot gnu.org> ---
> If _XOPEN_SOURCE is removed from thr.c completely, the testsuite results 
> revert
> to 1 failure.

Did this failure already exist before my patch?  If so, such a change is
certainly better than arch-specific _XOPEN_SOURCE values.  Andrew, what
do you thing?

Thanks.
        Rainer