Add: PRAGMA secure_delete

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

sqlite3_opt_secure_delete_fast.go

@@ -0,0 +1,15 @@
+// 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.
+
+// +build sqlite_secure_delete_fast
+
+package sqlite3
+
+/*
+#cgo CFLAGS: -DSQLITE_SECURE_DELETE=FAST
+#cgo LDFLAGS: -lm
+*/
+import "C"