g++ 5.3 AIX call_once issues

[Brian Groose]

I'm hitting what looks like pr67478 (which is fixed by pr 68192).

The example in PR67478 fails with the same error.  However, I'm running g++
5.3.0, so the issue should be fixed with my compiler.

I can see the symbols in libstdc++.a as type L as expected.

Do I need to compile g++ with some special option for this?

TLS using the thread_local keyword works fine, it's just that the linker
can't seem to find the symbols for call once:
ld: 0711-317 ERROR: Undefined symbol: std::__once_callable
ld: 0711-317 ERROR: Undefined symbol: std::__once_call
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more
information.
collect2: error: ld returned 8 exit status

Thanks!