9.1121 vfscanf

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

Gnulib module: vfscanf, nonblocking

Portability problems fixed by Gnulib module vfscanf, together with module nonblocking:

• When reading from a non-blocking pipe whose buffer is empty, this function fails with errno being set to EINVAL instead of EAGAIN on some platforms: mingw, MSVC 9.

Portability problems not fixed by Gnulib:

• This function is missing on some platforms: Minix 3.1.8, AIX 4.3.2, IRIX 6.5, OSF/1 5.1, Solaris 8, Interix 3.5.
• On Windows platforms (excluding Cygwin), this function does not set errno upon failure.
• On Windows, this function doesn't support the hh, ll, j, t, z size specifiers.