Support cast with INCR/DECR grn_obj_set_value() for VAR_SIZE SCALAR column
Support cast with INCR/DECR grn_obj_set_value() for VAR_SIZE SCALAR column

They are used memcached protocol.

naoa/groonga,cosmo0920/groonga,kenhys/groonga,cosmo0920/groonga,cosmo0920/groonga,naoa/groonga,cosmo0920/groonga,myokoym/groonga,naoa/groonga,redfigure/groonga,komainu8/groonga,kenhys/groonga,komainu8/groonga,hiroyuki-sato/groonga,komainu8/groonga,komainu8/groonga,naoa/groonga,naoa/groonga,myokoym/groonga,groonga/groonga,groonga/groonga,redfigure/groonga,redfigure/groonga,hiroyuki-sato/groonga,myokoym/groonga,redfigure/groonga,redfigure/groonga,hiroyuki-sato/groonga,kenhys/groonga,naoa/groonga,groonga/groonga,cosmo0920/groonga,kenhys/groonga,groonga/groonga,komainu8/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,cosmo0920/groonga,kenhys/groonga,naoa/groonga,hiroyuki-sato/groonga,cosmo0920/groonga,groonga/groonga,redfigure/groonga,myokoym/groonga,redfigure/groonga,naoa/groonga,komainu8/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,myokoym/groonga,groonga/groonga,hiroyuki-sato/groonga,komainu8/groonga,myokoym/groonga,groonga/groonga,komainu8/groonga,myokoym/groonga,myokoym/groonga,cosmo0920/groonga,kenhys/groonga,redfigure/groonga,hiroyuki-sato/groonga