avoid gcc7 warning about truncated snprintf format strings
avoid gcc7 warning about truncated snprintf format strings

percona/PerconaFT,BohuTANG/ft-index,percona/PerconaFT,BohuTANG/ft-index,BohuTANG/ft-index,BohuTANG/ft-index,percona/PerconaFT,percona/PerconaFT