QAtomic: pass explicit failure memory order to std::atomic::compare_exchange_strong

GCC 4.8 seems to get the failure memory order wrong when using the
overload that only accepts one memory order and produces errors such
as:

  bits/atomic_base.h:577:70: error: failure memory model cannot be stronger than success memory model for '__atomic_compare_exchange'
  return __atomic_compare_exchange_n(&_M_i, &__i1, __i2, 0, __m1, __m2);
                                                                      ^
(as seen on Android).

Fix by explicitly passing the failure orders corresponding to the
success orders, as specified by the standard:

 relaxed → relaxed
 release → relaxed
 acquire → acquire
 acq_rel → acquire

(cf. http://en.cppreference.com/w/cpp/atomic/atomic/compare_exchange).

Task-number: QTBUG-59399
Change-Id: If046e735888cf331d2d6506d8d5ca9aa7402f9ad
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
(cherry picked from commit 5cc0de2e084cb887a75b076b82cf470ecdcd4dd3)
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions