macosx: Fix startup delays by loading Open.nib only on demand

There is no need to already load it here, not every user uses the open panel.
Additionally, input devices listing may take one or two seconds the
first time after the system started, so this is also better done only when needed.

close #11098

modules/gui/macosx/intf.m

@@ -777,9 +777,6 @@ static VLCMain *_o_sharedMainInstance = nil;
     [[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:self selector:@selector(computerWillSleep:)
            name:NSWorkspaceWillSleepNotification object:nil];
 
-    /* we will need this, so let's load it here so the interface appears to be more responsive */
-    nib_open_loaded = [NSBundle loadNibNamed:@"Open" owner: NSApp];
-
     /* update the main window */
     [o_mainwindow updateWindow];
     [o_mainwindow updateTimeSlider];