nptl: Move __nptl_initial_report_events into ld.so/startup code

nptl: Move __nptl_initial_report_events into ld.so/startup code

The initialization of the report_events TCB field is now performed
in __tls_init_tp instead of __pthread_initialize_minimal_internal
(in libpthread).

The events interface is difficult to test because GDB stopped using it
in 2015.  The td_thr_get_info change to ignore lookup issues is enough
to support GDB with this change.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>