As noted here:
https://lore.kernel.org/buildroot/bug-15766-163@https.bugs.busybox.net%2F/T/
https://bugs.busybox.net/show_bug.cgi?id=15766

There is currently a dependency bug in Weston that does not yet appear to have been addressed in upstream Buildroot.

This breaks tsimx6_graphical_defconfig at this time but there is a workaround:
make tsimx6_graphical_defconfig xcb-util-cursor all

This will force xcb-util-cursor library to be built before Weston which will allow a build.

Once this bug is fixed upstream, this issue will be closed.