mbstowcs
========

POSIX specification:
 https://pubs.opengroup.org/onlinepubs/9699919799/functions/mbstowcs.html

Gnulib module: ---

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib:

  * On Windows and 32-bit AIX platforms, wchar_t is a 16-bit type and therefore cannot accommodate all Unicode characters. However, the Gnulib function mbstoc32s, provided by Gnulib module mbstoc32s, operates on 32-bit wide characters and therefore does not have this limitation.