clang: suppress a warning
clang: suppress a warning

proc.c:2219:15: warning: implicit conversion from enumeration type
      'grn_log_level' to different enumeration type 'grn_rc' [-Wconversion]
          ERR(GRN_ERROR, "invalid column type");
          ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./ctx.h:78:21: note: expanded from macro 'GRN_ERROR'
#define  GRN_ERROR  GRN_LOG_ERROR
                    ^
./ctx.h:144:45: note: expanded from macro 'ERR'
#define ERR(rc,...) ERRSET(ctx, GRN_ERROR, (rc),  __VA_ARGS__)
                                            ^
./ctx.h:118:15: note: expanded from macro 'ERRSET'
  ctx_->rc = (r);\
           ~  ^

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