Remove most of the code using feature=bundled as a version check

src/inner_connection.rs

@@ -281,7 +281,7 @@ impl InnerConnection {
         unsafe { ffi::sqlite3_get_autocommit(self.db()) != 0 }
     }
 
-    #[cfg(feature = "bundled")] // 3.8.6
+    #[cfg(feature = "modern_sqlite")] // 3.8.6
     pub fn is_busy(&self) -> bool {
         let db = self.db();
         unsafe {