As extend fdtable usage to more cases, there regularly arises a need
to forward ioctl/fcntl arguments to another ioctl vmethod, which is
complicated because it defined as taking variadic arguments. The only
portable solution is to convert variadic arguments to va_list at the
first point of entry from client code, and then pass va_list around.
To facilitate calling ioctl with variadic arguments from system code,
z_fdtable_call_ioctl() helper function is added.
Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
13b38ed686