tdf#92670 GtkSalGraphics::NWPaintGTKMenubar: fix modified clip rectangle
tdf#92670 GtkSalGraphics::NWPaintGTKMenubar: fix modified clip rectangle

Happens only with when double buffering is enabled, and e.g. with the
oxygen GTK2 theme, but not with the default one.

Change-Id: Iad9911121e57388c84c25860413763f75e06b0ea

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core