a [x]kanjiskip glue whose spec is from JFM has distinguished attr_icflag value

a [x]kanjiskip glue whose spec is from JFM has distinguished attr_icflag value

icflag_table.KANJI_SKIP      = 9
icflag_table.KANJI_SKIP_JFM  = 10  -- NEW
icflag_table.XKANJI_SKIP     = 11  -- old: 10
icflag_table.XKANJI_SKIP_JFM = 12  -- NEW
icflag_table.PROCESSED       = 13  -- old: 11
icflag_table.IC_PROCESSED    = 14  -- old: 12
icflag_table.PROCESSED_BEGIN_FLAG = 128 -- old: 32

Memory leak which is caused by luatexja-adjust (ltj-adjust.lua) is now
resolved in this commit, but perhaps there is better solution.