sqlite3.go: use PRAGMA to set busy_timeout (#910)
sqlite3.go: use PRAGMA to set busy_timeout (#910)

The busy_timeout pragma was added in sqlite 3.7.15 as an alternative
to calling sqlite3_busy_timeout directly:

https://sqlite.org/pragma.html#pragma_busy_timeout

While there's no functional change here, using the pragma does align
setting busy_timeout with other settings and removes the special case
for calling sqlite3_busy_timeout directly.
mattn/go-sqlite3,mattn/go-sqlite3,mattn/go-sqlite3