dbus: fix build on microblaze

Fixes http://autobuild.buildroot.net/results/5963d35b8933c452b8574c964e407c23a5d0412f



The microblaze toolchain has sys/inotify.h, but doesn't provide inotify_rm_*
functions, so disable inotify support.

Also disable the legacy dnotify support (which is used when inotify support
is disabled) as it has bitrotten upstream and no longer builds.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>