svtools: Simplify TabBar_Impl with std::unique_ptr

Change-Id: If477373f6e5a39ccd61332356a821f7c7d38d28d
Reviewed-on: https://gerrit.libreoffice.org/47488Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Takeshi Abe <tabe@fixedpoint.jp>

include/svtools/tabbar.hxx

@@ -25,7 +25,6 @@
 #include <vcl/window.hxx>
 #include <o3tl/typed_flags_set.hxx>
 #include <memory>
-#include <vector>
 
 /*
 
@@ -308,7 +307,6 @@ class TabBarEdit;
 
 struct ImplTabBarItem;
 struct TabBar_Impl;
-typedef std::vector<ImplTabBarItem*> ImplTabBarList;
 
 
 class SVT_DLLPUBLIC TabBar : public vcl::Window