Gsql prepared statements

Audit list
 - [ ] GSQLBackend
 - [ ] SSql
 - [ ] gMySQL
 - [ ] gPgSQL
 - [ ] gSqlite3
 - [ ] gOracle
 - [ ] BIND (dnssec)
 - [ ] mydns
According to docs, you should set bind[x].length is used for character or binary C data. http://dev.mysql.com/doc/refman/5.6/en/c-api-prepared-statement-data-structures.html

This code is a bit different comparing with documentation example: http://dev.mysql.com/doc/refman/5.6/en/mysql-stmt-execute.html