[Dillo-dev] [patch]: fix compiler warning in CustShrinkTabPager

The CustShrinkTabPager class generates a gcc warning because it has virtual functions but its destructor is not virtual. This patch adds the virtual destructor and stops the warning. NB: there may be a case for rejecting this patch if we're really concerned about the performance of virtual functions (one extra indirection per call). FLTK deliberately avoids virtual destructors whenever possible for just this reason. I seriously doubt that this patch makes any impact on Dillo, but that's just IMHO. Regards, Jeremy Henty