make expand_has_...() responsible for expanding its argument

If we want to make expansion of arguments on-demand, we need to adjust
->expand() calling conventions first, passing it unexpanded arguments.
Switch create_arglist() to setting argcounts from normal=1 to quoted=1,
provide a helper (first_arg()) that does actual expansion and make
->expand() instances use it.  After that these fake arglists are used
only for two things: they indicate that these macros are function-like
and they short-circuit expand_arguments().  Once we switch to on-demand
argument expansion, the second role will disappear and we can just use
&eof_token_entry as ->arglist for those.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris Li <sparse@chrisli.org>