We can select a custom official version for the optee-os package; add an option to select the same version for optee-examples, to easily keep them synchronized. Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com> Cc: Étienne Carrière <etienne.carriere@foss.st.com> Signed-off-by: Julien Olivain <ju.o@free.fr>