This adds a NEEDS_XKB_UTILS automake conditional that's set to true if
either the wayland backend is enabled or the evdev input backend is
enabled since they both depend on clutter-xkb-utils.c and we need
to avoid listing the file twice since that leads to duplicate symbols
and the build fails.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>