Add build constraints for non cgo

sqlite3_opt_preupdate.go

@@ -1,9 +1,11 @@
 // Copyright (C) 2019 G.J.R. Timmer <gjr.timmer@gmail.com>.
 // Copyright (C) 2018 segment.com <friends@segment.com>
-
+//
 // Use of this source code is governed by an MIT-style
 // license that can be found in the LICENSE file.
 
+// +build cgo
+
 package sqlite3
 
 // SQLitePreUpdateData represents all of the data available during a