make filter sockets for data non-blocking.
fix potential hang reported by Jason Barbier.
don't chroot queue_python, the python script should do it itself
otherwise imports will fail
- Tweak the scheduler API. The scheduler backend can now return a mix
  of different envelope, instead of batches of a single type.
- Interlace envelopes from all queue types in the default scheduler.
- Allow to use an external proc as scheduler backend.
- Implement a python glue for the scheduler API.
fix warnings
Merge branch 'master' of ssh://ssh.poolp.org/git/opensmtpd
unused function
queue_python_message_create should Py_DECREF ret to avoid mem leak
Merge branch 'master' of ssh://ssh.poolp.org/git/opensmtpd
rearrange code to handle refcount correctly
When an envelope is scheduled for removal or expire, count it as
inflight. The queue sends an ack when it can actually process it.
The max inflight mechanism ensures that the scheduler never sends
envelopes faster than the queue can process.
Merge branch 'master' of ssh.poolp.org:/git/opensmtpd
master uses reallocarray() but it was introduced after OpenBSD 5.5
preventing build of OpenSMTPD -master on OpenBSD -stable.

introduce reallocarray.c and conditionally build it if we detect
the system doesn't provide it
move queue_python to the OpenSMTPD-extras repository
add the no_chroot/chroot/user functions to the scheduler api.
fix scheduler_python
Merge branch 'master' of ssh.poolp.org:/git/opensmtpd
move filter-python to OpenSMTPD-extras
Merge branch 'master' of ssh://ssh.poolp.org/git/opensmtpd
table_mysql moves to OpenSMTPD-extras
fix build
move table-ldap out of smtpd to OpenSMTPD-extras
move table_postgres to OpenSMTPD-extras