Knowing if --enable-libstdcxx-filesystem-ts has been passed to the configure in
the AIX config Makefile would require a lot of change in libstdc++ Makefiles. Thus,
it's easier to ignore errors when retrieving objects and check their existence
before adding them.

libstdc++/Changelog:
2020-09-22 Clement Chigot <clement.chigot@atos.net>
 * config/os/aix/t-aix: Add complementary mode object file to libstdc++fs.a



Clément Chigot
ATOS Bull SAS
1 rue de Provence - 38432 Échirolles - France