Version: 5.2.1

Changes:
    * Added _android.h included by _system.h
    * Do not use linux float functions in num_get_float.cpp as Android does not
      have them.
    * _mbstate_t.h cannot define its own mbstate_t as bionic already defines
      it.
    * _pair.h needs to define bionic's (sgi's) internal pair header guard.
