initialization problem w/ thread-specific .tbss data on i386

[Phil Shafer]

Konstantin Belousov writes:
>No, try to compile libc with e.g. clang 5 and see if it also fixes
>libxo.

See PR 227552 comment 20, where Dimitry Andric says:

    Hmm, now that we've identified .tbss as a contributor to the
    problem, it looks relevant that the r331838 version of libxo.so.0
    (compiled with the clang 6.0.0 update) does NOT have a "section
    to segment mapping" for .tbss:
    ...

Before clang-6, it was working fine.

Thanks,
 Phil