TS-2156: Fix stats trap in different type of threads

There are two ways to create threads in ATS:
1) By EventProcessor::spawn_event_threads(), such as ET_NET threads.
2) By EventProcessor::spawn_thread(), such as flush thread.

But I found that we can't stats the same things across these two type of
threads.

This patch will make stats in both type of threads transparent for upper
layer developers.

BTW: renames "dthreads" to "all_dthreads" to keep naming consistency
     with "all_ethreads".

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
Change-Id: Ib5557b7a5b045cfaac12ad9a088f98c6fe2d64f5
TS-2162: Auto-created collation LogObject would be misused by access log

When collation host receives LogBuffer data from network, it'll create
LogObject according the data's format automatically.

Since the LogFilter of these auto-created LogObjects are empty, they
will be misused by access log generated by collation host itself –
toss_this_entry() will always return false when m_does_conjunction is
set.

This patch introduces a new member variable: m_auto_created in LogObject,
so that we can distinguish this type of LogObject to avoid misusing.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>