require librelp 1.2.5

prep work for handling new error codes
emit better error message if librel does not provide TLS

Right now, this can only happen due to too-old version of GnuTLS. Should
this change in the future, we can update the error message as well, but
the current one was too-generic and confused users.
autoconf: remove no longer needed macro
bugfix: ompipe did emit many suspension messages for /dev/xconsole

(hopefully now) closes: https://github.com/rsyslog/rsyslog/issues/35
When it was present, but nobody reading from it. The problem
is the way the rsyslog v7 engine tries to resolve failures in outputs.
It does some retries, and along those lines some state information gets
lost and it is close to impossible to retain it. However, the actual
root problem is that ompipe does not reliably detect if it is able to
recover. The problem here is that it actually does not know this
before it does an actual write. These two things together mess up the
logic that suppresses invalid resumption/suspension messages
(actually, the plugin switches state really that often).
Nevertheless, the prime problem with /dev/xconsole (and probably
most other pipes as well) is that it gets full. So I have now added
code that checks, during resume processing, if the pipe is writable.
If it is not, resume is deferred. That should address the case.
fix missing argument

unfortunately, during cleanup of code for
https://github.com/rsyslog/rsyslog/issues/35
I removed a bit too much and noticed the compiler warning
too late.
bugfix: ompipe used invalid default template

This is a regression from an old change (didn't track it down precisely,
but over a year ago). It used the Forwarding template instead of
the file template (so we have a full syslog header). This fix corrects
it back to previous behaviour, but new scripts that used the wrong
format may now need to have the RSYSLOG_ForwardingFormat template
explicitely be applied.
closes: https://github.com/rsyslog/rsyslog/issues/50
Merge branch 'v7-stable' into v8-stable

Conflicts:
	tools/ompipe.c