9.1161 wcsspn

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

Gnulib module: wcsspn

Portability problems fixed by Gnulib:

• This function is missing on some platforms: IRIX 5.3, Solaris 2.5.1.

Portability problems not fixed by Gnulib:

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