macosx: fixed crash when setting up the video output

AppKit could be accessed by a non-main-thread

modules/gui/macosx/MainWindow.h

@@ -184,7 +184,7 @@
 - (void)drawFancyGradientEffectForTimeSlider;
 
 - (id)videoView;
-- (id)setupVideoView;
+- (void)setupVideoView;
 - (void)setVideoplayEnabled;
 - (void)resizeWindow;
 - (void)setNativeVideoSize:(NSSize)size;

modules/gui/macosx/MainWindow.m

@@ -1762,7 +1762,7 @@ static VLCMainWindow *_o_sharedInstance = nil;
     return o_video_view;
 }
 
-- (id)setupVideoView
+- (void)setupVideoView
 {
     // TODO: make lion fullscreen compatible with macosx-background and !embedded-video
     if( var_InheritBool( VLCIntf, "macosx-background" ) && !b_nativeFullscreenMode )
@@ -1851,7 +1851,6 @@ static VLCMainWindow *_o_sharedInstance = nil;
     }
 
     [[o_video_view window] setAlphaValue: config_GetFloat( VLCIntf, "macosx-opaqueness" )];
-    return o_video_view;
 }
 
 - (void)setVideoplayEnabled

modules/gui/macosx/intf.m

@@ -1783,7 +1783,8 @@ unsigned int CocoaKeyToVLC( unichar i_key )
 
 - (id)getVideoViewAtPositionX: (int *)pi_x Y: (int *)pi_y withWidth: (unsigned int*)pi_width andHeight: (unsigned int*)pi_height
 {
-    id videoView = [o_mainwindow setupVideoView];
+    [o_mainwindow performSelectorOnMainThread:@selector(setupVideoView) withObject:nil waitUntilDone:YES];
+    id videoView = [o_mainwindow videoView];
     NSRect videoRect = [videoView frame];
     int i_x = (int)videoRect.origin.x;
     int i_y = (int)videoRect.origin.y;