Return event_ptid from ravenscar_thread_target::wait
ravenscar_thread_target::wait should return the event ptid from the
wrapped "wait" call in the situation where returning the Ravenscar
thread ptid is not appropriate. This probably does not really make a
difference in practice, but it seemed like a reasonable cleanup.
gdb/ChangeLog
2020-08-07 Tom Tromey <tromey@adacore.com>