[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 #12 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> Let's go with the one defining _XOPEN_SOURCE only for Solaris until someone
> programs David's suggestion of the host-specific configure file.

Huh?  As I've just checked, both Solaris and Linux/x86_64 do fine
without any definition of _XOPEN_SOURCE at all, as does AIX.  Only if
_XOPEN_SOURCE is defined at all does Solaris need a value >= 600 with
C99 and beyond.

The attached patch does just that.

    Rainer