Refactor YieldFor() to avoid code duplication among the ports.

Don't repeat the same code in all the ports, move it to the common base class
and add a new virtual DoYieldFor() for the really port-specific code.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76061 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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/trunk@76062 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775