am 4a927712: am 0621a279: libstdc++: use extern "C++" in all our C++ system headers.

Merge commit '4a927712b7375844bb6c10eb0e495fcc4904d805'

* commit '4a927712b7375844bb6c10eb0e495fcc4904d805':
  libstdc++: use extern "C++" in all our C++ system headers.