database/sql: use method values instead of generating closures
database/sql: use method values instead of generating closures

Reduces garbage.

R=adg, r
CC=dsymonds, gobot, golang-dev
https://codereview.appspot.com/9088045

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang