tdf#114985: Tell NSWindow to never use automatic window tabbing

Based on https://codereview.chromium.org/2325313002/

Change-Id: I8838449d57b1d1b010491a405c87645d38199fdf
Reviewed-on: https://gerrit.libreoffice.org/48330Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tor Lillqvist <tml@collabora.com>

vcl/osx/vclnsapp.mm

@@ -75,6 +75,11 @@ SAL_WNODEPRECATED_DECLARATIONS_PUSH
 SAL_WNODEPRECATED_DECLARATIONS_POP
     assert( pEvent );
     [NSApp postEvent: pEvent atStart: NO];
+
+    if( [NSWindow respondsToSelector:@selector(allowsAutomaticWindowTabbing)] )
+    {
+        NSWindow.allowsAutomaticWindowTabbing = NO;
+    }
 }
 
 -(void)sendEvent:(NSEvent*)pEvent