[Bug libstdc++/106772] New: atomic<T>::wait shouldn't touch waiter pool if used platform wait

[valera.mironow at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106772

            Bug ID: 106772
           Summary: atomic<T>::wait shouldn't touch waiter pool if used
                    platform wait
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: valera.mironow at gmail dot com
  Target Milestone: ---

atomic<T>::wait shouldn't touch waiter pool if used platform wait.

Because otherwise it affected by waiter pool bugs.
And performance can degrade on machine with many cores, because waiter pool
have only 16 cells.
Also it makes fetch_add with seq_cst, that can hide synchronization issue