Adding the sqlite sourcecode

ext/wasm/api/extern-pre-js.js

@@ -0,0 +1,7 @@
+/* extern-pre-js.js must be prepended to the resulting sqlite3.js
+   file. This file is currently only used for holding snippets during
+   test and development.
+
+   It gets its name from being used as the value for the
+   --extern-pre-js=... Emscripten flag.
+*/