[Bug libstdc++/67478] gcc-5.1.0/gcc-5.2.0 undefined symbol std::__once_callable in AIX 6.1

[tgard at opentext dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67478

--- Comment #4 from Torbjörn Gard <tgard at opentext dot com> ---
I found -qtls=model option for xlc in AIX:
http://www-01.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/compiler_ref/opt_tls.html

The corresponding option in gcc is -ftls-model=model. I tried with
-ftls-model=global-dynamic. However, the link fails with the same error.