EX-7451 lipe: Add memory and access log reader stats in lamigo

EX-7451 lipe: Add memory and access log reader stats in lamigo

- Name lamigo threads
- Add memory allocation and deallocation stats in lamigo_alr
- Add stats on total received ALR's, max elements to heat sort,
  current number of allocated heat records
- Add stats on heat thread cycle elapsed time
- Add stats on receiving access log records
  by heat thread
- Add stats on ALR and changelog file cache usage
- Increase number of hash buckets to accomodate
  a million files in the cache by default. This speeds up
  processing input ALR's and prevents excessive memory usage
  for input ALR's
- Modified prints in lamigo_alr_dump_heat_table()
- Add timestamp when stats is dumped on USR1 signal
- Add stats on individual access log readers when
  used USR1 signal stats dump
- Add stats prints in periodical INFO message

Test-Parameters: trivial testlist=hot-pools
Signed-off-by: Alexandre Ioffe <aioffe@ddn.com>
Change-Id: I57215f988278bfe42ddd5f1fd7607c3dbb3fdcdb
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/50698
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>