stale lisp/Makefile

[Glenn Morris]

There have been quite a few spurious problems recently reported by
people whose lisp/Makefile is out-of-date with respect to
lisp/Makefile.in.

Personally, I always use `make maintainer-clean; make bootstrap', so I
don't run into these issues, but this seems to be too slow, or
overkill, for some.

Two questions:

1) Have I missed something in my treatment of cal-loaddefs.el etc in
lisp/Makefile.in?

2) Is it possible to add/worth adding a check for an out-of-date
lisp/Makefile? Is this as simple as adding `$(lispdir)/Makefile.in' to
the existing dependency of Makefile on $(srcdir)/Makefile.in in the
top-level Makefile.in?

TIA.