prevent name clash on Windows w/ RT_* defines
Windows' native headers using some our RT_* define's names for other things. Since the naming isn't very nice anyways, introducing some new ones (X11_RESTYPE_NONE, X11_RESTYPE_FONT, X11_RESTYPE_CURSOR) and define the old ones as an alias to them, in case some out-of-tree code still uses them.
With thins change, we don't need to be so extremely careful about include ordering and have explicit #undef's in order to prevent name clashes on Win32 targets.
Signed-off-by: Enrico Weigelt, metux IT consult info@metux.net