* config.gcc (default_use_cxa_atexit): New variable, defaults to no.
(*-*-netbsd[2-9]* | *-*-netbsdelf[2-9]*): Set default_use_cxa_atexit
to yes.
* configure.in: Allow default_use_cxa_atexit to determine the
value of DEFAULT_USE_CXA_ATEXIT if not explicitly enabled or
disabled.
* configure: Regenerate.

From-SVN: r67401