* automake.in (required_targets): Add ps and ps-am.

* automake.in (required_targets): Add ps and ps-am.
(initialize_per_input): Reset them.
(handle_texinfo_helper): Fill @pss_list, and define the
PSS make variable.
* lib/am/texinfos.am (RECURSIVE_TARGETS): Add ps-recursive.
(ps, ps-am): New targets.
* automake.texi (Auxiliary Programs) <texinfo.tex>: Mention
`make ps' and `make pdf'.
(Texinfo): Document `make ps', `make pdf', and `make dvi'.
(Extending): The `ps' and `pdf' targets support a `-local' version.