XORG_WITH_DOXYGEN provides additional functions like a configure
option which allow platform builders to control the usage of
the doxygen program.
This is a requirement from platforms that do not have such doc tool.
A platform with a back level doxygen may use --without-doxygen
to get the rest of the documentation built.
Signed-off-by: Gaetan Nadon <memsize@videotron.ca>
Signed-off-by: Keith Packard <keithp@keithp.com>