sql: prevent panic if client sends too many fmt codes
sql: prevent panic if client sends too many fmt codes

This is theoretical and difficult to test since it involves breaking
a client, but it's probably safer to try to prevent a panic here. The
panic would occur a few lines down when indexing into paramFormatCodes. If
the client sends 2 format codes, but the statement only has 1 parameter,
it would panic.

nieyy/cockroach,cuongdo/cockroach,cuongdo/cockroach,sunya123/cockroach,sunya123/cockroach,maxlang/cockroach,cockroachdb/cockroach,sunya123/cockroach,arjun4084346/cockroach,maxlang/cockroach,cuongdo/cockroach,sunya123/cockroach,arjun4084346/cockroach,bg451/cockroach,maxlang/cockroach,maxlang/cockroach,paperstreet/cockroach,cuongdo/cockroach,arjun4084346/cockroach,nieyy/cockroach,vaibhavarora/cockroach,petermattis/cockroach,arjun4084346/cockroach,veteranlu/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,petermattis/cockroach,sunya123/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,paperstreet/cockroach,maxlang/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,maxlang/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,vivekmenezes/cockroach,arjun4084346/cockroach,cuongdo/cockroach,veteranlu/cockroach,nieyy/cockroach,petermattis/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,glycerine/cockroach,vivekmenezes/cockroach,bg451/cockroach,cuongdo/cockroach,paperstreet/cockroach,sunya123/cockroach,veteranlu/cockroach,cockroachdb/cockroach,bg451/cockroach,maxlang/cockroach,glycerine/cockroach,petermattis/cockroach,sunya123/cockroach,petermattis/cockroach,cockroachdb/cockroach,glycerine/cockroach,vaibhavarora/cockroach,petermattis/cockroach,nieyy/cockroach,glycerine/cockroach,nieyy/cockroach,bg451/cockroach,vaibhavarora/cockroach,paperstreet/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,arjun4084346/cockroach,cuongdo/cockroach,nieyy/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,maxlang/cockroach,vaibhavarora/cockroach,cockroachdb/cockroach,paperstreet/cockroach,nieyy/cockroach,cuongdo/cockroach,paperstreet/cockroach,bg451/cockroach,glycerine/cockroach,bg451/cockroach,glycerine/cockroach,petermattis/cockroach,petermattis/cockroach,vaibhavarora/cockroach,bg451/cockroach,glycerine/cockroach,arjun4084346/cockroach,veteranlu/cockroach,paperstreet/cockroach,nieyy/cockroach,glycerine/cockroach,sunya123/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,cockroachdb/cockroach,vivekmenezes/cockroach,veteranlu/cockroach