The garbage collector of AIX linker might remove the reference to
__tls_get_addr if it's added inside an unused csect, which can be
the case of .data with very simple programs.

gcc/ChangeLog:
2021-10-19  Clément Chigot  <clement.chigot@atos.net>

        * config/rs6000/rs6000.c (rs6000_xcoff_file_end): Move
        __tls_get_addr reference to .text csect.

Approved offline by David Edelson.