From: Daeho Jeong <daehojeong@xxxxxxxxxx>
Added gc_reclaimed_segments and gc_segment_mode sysfs nodes.
1) "gc_reclaimed_segments" shows how many segments have been
reclaimed by GC during a specific GC mode.
2) "gc_segment_mode" is used to control for which gc mode
the "gc_reclaimed_segments" node shows.
Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>