Use o3tl::make_unique when var is unique_ptr

Change-Id: I2d8b20aeb686bd4b59fe8dcaf695a17d94a440c9
Reviewed-on: https://gerrit.libreoffice.org/41967Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

vcl/source/control/button.cxx

@@ -42,6 +42,7 @@
 #include <svdata.hxx>
 #include <window.h>
 #include <controldata.hxx>
+#include <o3tl/make_unique.hxx>
 
 #include <comphelper/dispatchcommand.hxx>
 
@@ -92,7 +93,7 @@ mbSmallSymbol(false), maImage(), meImageAlign(ImageAlign::Top), meSymbolAlign(Sy
 
 Button::Button( WindowType nType ) :
     Control( nType ),
-    mpButtonData( new ImplCommonButtonData )
+    mpButtonData( o3tl::make_unique<ImplCommonButtonData>() )
 {
 }