iswblank
========

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

Gnulib module: wctype

Portability problems fixed by Gnulib:

  * This function is missing on some platforms: AIX 4.3.2, IRIX 6.5, OSF/1 5.1, Solaris 9, mingw.

  * This function returns 0 for all possible arguments on some platforms: Linux libc5.

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.