mbtowc
======

POSIX specification:
 http://www.opengroup.org/onlinepubs/9699919799/functions/mbtowc.html

Gnulib module: ---

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib:

  * This function accumulates hidden state on some platforms: glibc 2.8 (see http://sourceware.org/bugzilla/show_bug.cgi?id=9674).

  * On AIX and Windows platforms, wchar_t is a 16-bit type and therefore cannot accommodate all Unicode characters.