macosx: fixed crash in CoreDialogs when closing the progress panel

(cherry picked from commit 52576ea50e1cb5d2fbb3ceba958128dc81ed13b9)

modules/gui/macosx/coredialogs.m

@@ -220,8 +220,8 @@ static VLCCoreDialogProvider *_o_sharedInstance = nil;
 -(void)destroyProgressPanel
 {
     b_progress_cancelled = YES;
-    [o_prog_bar stopAnimation: self];
-    [o_prog_win close];
+    [o_prog_bar performSelectorOnMainThread:@selector(stopAnimation:) withObject:self waitUntilDone:YES];
+    [o_prog_win performSelectorOnMainThread:@selector(close) withObject:nil waitUntilDone:YES];
 }
 
 -(IBAction)progDialogAction:(id)sender

modules/gui/macosx/intf.m

@@ -449,7 +449,7 @@ void updateProgressPanel (void *priv, const char *text, float value)
 void destroyProgressPanel (void *priv)
 {
     NSAutoreleasePool *o_pool = [[NSAutoreleasePool alloc] init];
-    [[[VLCMain sharedInstance] coreDialogProvider] performSelectorOnMainThread:@selector(destroyProgressPanel) withObject:nil waitUntilDone:NO];
+    [[[VLCMain sharedInstance] coreDialogProvider] destroyProgressPanel];
     [o_pool release];
 }