Seeks to offset amount (an Integer) in the ARGF stream according to the value of
whence. See IO#seek for further
details.
static VALUE
argf_seek_m(int argc, VALUE *argv, VALUE argf)
{
if (!next_argv()) {
rb_raise(rb_eArgError, "no stream to seek");
}
ARGF_FORWARD(argc, argv);
return rb_io_seek_m(argc, argv, ARGF.current_file);
}