Unify LISP, PYTHON and JAVA primaries.

Unify LISP, PYTHON and JAVA primaries.
* automake.in (&handle_emacs_lisp): Be like &handle_python, i.e.,
return if there are no files, hook elist-comp on the Autoconf
macro, rely on lisp.am to define variables.
(&handle_python, &handle_java): Likewise.
(&scan_one_autoconf_file): Pseudo AC_SUBST of `pythondir' and
`PYTHON' must be handled here, not in `&handle_python'.
* java.am: Define needed variables and rules.