Block periodic saves while importing

Resampling or copying files during import can take a long time.
If a save, or pending save is called while importing,
it is postponed until after import has completed.

gtk2_ardour/editor_audio_import.cc

@@ -540,7 +540,8 @@ Editor::import_sndfiles (vector<string>            paths,
                          bool                      replace,
                          ARDOUR::PluginInfoPtr     instrument)
 {
-	cerr << "Importing " << paths.size() << " at once\n";
+	/* skip periodic saves while importing */
+	Session::StateProtector sp (_session);
 
 	import_status.paths = paths;
 	import_status.done = false;
@@ -615,6 +616,9 @@ Editor::embed_sndfiles (vector<string>            paths,
 	string linked_path;
 	SoundFileInfo finfo;
 
+	/* skip periodic saves while importing */
+	Session::StateProtector sp (_session);
+
 	CursorContext::Handle cursor_ctx = CursorContext::create(*this, _cursors->wait);
 	gdk_flush ();