devel/dbus: use minixmlto over xmlto

Depending on the options set by the user w3m may depend on gtk,
if the X11 option is set) which will result in a circular dependency
gtk2 -> glib2 -> dbus -> xmlto -> w3m -> gtk2

minixmlto never bring w3m in the dependency list

PR: 263950
Reported by: dgilbert@eicat.ca