clang: suppress a warning
clang: suppress a warning

    lib/expr.c:380:28: warning: passing
          'const uint8_t *' (aka 'const unsigned char *') to parameter of type
          'const char *' converts between pointers to integer types with different
          sign [-Wpointer-sign]
      grn_bulk_write(ctx, obj, p, vs);
                               ^

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