libx11-compose-data: Update LICENSE to better reflect reality

There are no traces of neither the BSD-2-Clause license nor the
BSD-4-Clause license being used in the code. There is one occurrence
of the BSD-1-Clause license. On the other hand, HPND and
HPND-sell-variant are all over the place.

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>