phosphor-sel-logger package

[Will Liang (梁永鉉)]

HI Jason,

When I use the latest commit(7d5054ac), it can only record one sel log(the latest sel).
After tracing code I found that the recordId [1] always be 1.
[1] https://github.com/openbmc/phosphor-sel-logger/blob/7d5054ac15bee9945ac00c470c36c94b565ac8fa/src/sel_logger.cpp#L112

I have questions about the above situation.

1. where the "selLogFilename"[2] file be created? 
  Code [3] checks the file but can't find where to create it in this package.
  [2] https://github.com/openbmc/phosphor-sel-logger/blob/7d5054ac15bee9945ac00c470c36c94b565ac8fa/include/sel_logger.hpp#L37
  [3] https://github.com/openbmc/phosphor-sel-logger/blob/7d5054ac15bee9945ac00c470c36c94b565ac8fa/src/sel_logger.cpp#L55

2. After manually creating a file on /var/log/, the sel log behavior is normal. It can log several logs.
  but after I clear the sel log, the record id does not restart at 1. 
  Commit id : 6afe9560852c6431c43c8e79a28e2b7cb498e355

BRs,
will