Adding the sqlite sourcecode

ext/wasm/example_extra_init.c

@@ -0,0 +1,23 @@
+/*
+** If the canonical build process finds the file
+** sqlite3_wasm_extra_init.c in the main wasm build directory, it
+** arranges to include that file in the build of sqlite3.wasm and
+** defines SQLITE_EXTRA_INIT=sqlite3_wasm_extra_init.
+**
+** The C file must define the function sqlite3_wasm_extra_init() with
+** this signature:
+**
+**  int sqlite3_wasm_extra_init(const char *)
+**
+** and the sqlite3 library will call it with an argument of NULL one
+** time during sqlite3_initialize(). If it returns non-0,
+** initialization of the library will fail.
+*/
+
+#include "sqlite3.h"
+#include <stdio.h>
+
+int sqlite3_wasm_extra_init(const char *z){
+  fprintf(stderr,"%s: %s()\n", __FILE__, __func__);
+  return 0;
+}