Add: PRAGMA secure_delete

ADD: Connection PRAGMA
ADD: Build tag for secure_delete mode: FAST

sqlite3_opt_secure_delete.go

@@ -1,4 +1,5 @@
 // Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+// Copyright (C) 2018 G.J.R. Timmer <gjr.timmer@gmail.com>.
 //
 // Use of this source code is governed by an MIT-style
 // license that can be found in the LICENSE file.
@@ -8,7 +9,7 @@
 package sqlite3
 
 /*
-#cgo CFLAGS: -DSQLITE_SECURE_DELETE
+#cgo CFLAGS: -DSQLITE_SECURE_DELETE=1
 #cgo LDFLAGS: -lm
 */
 import "C"