am 973a83f0: am d466780c: Add missing SMP barriers to libstdc++

Merge commit '973a83f04d63a984be9ea7d4a8f8fea56ebe2133'

* commit '973a83f04d63a984be9ea7d4a8f8fea56ebe2133':
  Add missing SMP barriers to libstdc++