Don't rely on M4sugar outputting the patterns in files, since we

Don't rely on M4sugar outputting the patterns in files, since we
might process the output _without_ running m4, hence without these
files.
* lib/m4sugar/m4sugar.m4 (m4_init): No need for `m4_tmpdir'.
* bin/autom4te.in (@Request::includes): Remove, unused.
(@Request::source): Rename as...
(@Request::input): this.
(@preselect): Add `m4_pattern_forbid' and `m4_pattern_allow'.
(&handle_output): Fetch the patterns from the traces.
`$forbidden' and `$allowed' are constant: use m//o.
(&handle_m4): M4sugar no longer wants `m4_tmpdir'.
(m4_pattern_forbid, m4_pattern_allow): Adjust for tracing only.