for GTK3, draw odd-width lines as a sharp, n-pixel wide line, rather than a fuzzy n+1-pixel wide line


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76062 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775