TS-2122: Enlarge the 64KB limitation of log buffer size

The Logging module use uint16_t(LogBuffer->m_state.s.m_offset/byte_count) to
store log buffer size.

It's very dangerous for user, as there are not any warning when user
breaks the limitation.

In our environment, we set the log_buffer_size to 512KB(and set
max_entries_per_buffer to 1000), it make ATS crashing.

This patch enlarge the limitation from 64KB to 4GB by merging *offset* and
*byte_count* variables into one, so that we can use uint32_t to store the
buffer size.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2123: Remove useless max_entries_per_buffer option

When the configurable value of max_entries_per_buffer in LogHost is
smaller that LogClient, it'll lead to log dropped silently.

Actually, after we fix https://issues.apache.org/jira/browse/TS-2122 issue,
the max_entries_per_buffer option is unnecessary now.

Let's remove it to avoid traps caused by it.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2063: LogFile::write_ascii_logbuffer3() can silently drop log entries

1) Avoid silently dropping log entries in write_ascii_logbuffer3().
2) Remove overspill logic, and try to write log to disk as much as possible.
3) Simplify the code by removing unecessary *overspill* variables.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
Fix warning by adding space between " and PRIu32

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