Fixes Micha's two NetBSD warning msgs (posted on fltk.general 12/16/13):

    tree.cxx: 1443: warning: passing 'double' for argument 1 to 'void Fl_Tree::scrollbar_size(int)'
    tree.cxx: 1440: warning: passing 'double' for argument 1 to 'static void Fl::scrollbar_size(int)'



git-svn-id: http://seriss.com/public/fltk/fltk/branches/branch-1.3@10036 ea41ed52-d2ee-0310-a9c1-e6b18d33e121