* Collectd::Unixsock: Split messages sent by flush() to 1024 byte chunks to not overflow buffer in unixsock.c us_handle_client().

[rpv-tomsk]

Collection3 scripts generates commands of huge length when many files needs to be flushed.

This causes errors in web-server logs like this:

index.cgi: FLUSH failed: Parsing options failed. at ../lib/Collectd/Graph/Common.pm

And errors from collectd like this:

collectd[1243]: unixsock plugin: failed to write to socket #8: Broken pipe

Proposed patch splits FLUSH to separate commands. We have used this in production for a long time, and I think it will be useful for others too.

[rubenk]

Please rebase and squash.

[rpv-tomsk]

Updated.

[rubenk]

Thanks!