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

Merge commit '0621a279adfb981ea1f0564e7fc8280cda78e043' into gingerbread-plus-aosp

* commit '0621a279adfb981ea1f0564e7fc8280cda78e043':
  libstdc++: use extern "C++" in all our C++ system headers.