Add a compile-time shutdown procedure to be called by sqlite3_shutdown()

to undo the effects of the compile-time initialization procedure.

FossilOrigin-Name: c2ed86f5945662a4ddcdc7b303df3f64fb3bf17d

src/main.c

@@ -257,6 +257,10 @@ int sqlite3_initialize(void){
 */
 int sqlite3_shutdown(void){
   if( sqlite3GlobalConfig.isInit ){
+#ifdef SQLITE_EXTRA_SHUTDOWN
+    void SQLITE_EXTRA_SHUTDOWN(void);
+    SQLITE_EXTRA_SHUTDOWN();
+#endif
     sqlite3_os_end();
     sqlite3_reset_auto_extension();
     sqlite3GlobalConfig.isInit = 0;