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.

sqlite3.go

@@ -1415,12 +1415,6 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		return nil, errors.New("sqlite succeeded without returning a database")
 	}
 
-	rv = C.sqlite3_busy_timeout(db, C.int(busyTimeout))
-	if rv != C.SQLITE_OK {
-		C.sqlite3_close_v2(db)
-		return nil, Error{Code: ErrNo(rv)}
-	}
-
 	exec := func(s string) error {
 		cs := C.CString(s)
 		rv := C.sqlite3_exec(db, cs, nil, nil, nil)
@@ -1431,6 +1425,12 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		return nil
 	}
 
+	// Busy timeout
+	if err := exec(fmt.Sprintf("PRAGMA busy_timeout = %d;", busyTimeout)); err != nil {
+		C.sqlite3_close_v2(db)
+		return nil, err
+	}
+
 	// USER AUTHENTICATION
 	//
 	// User Authentication is always performed even when