Merge pull request #36203 from lsix/libunistring_0.9.9
libunistring: 0.9.8 -> 0.9.9
(cherry picked from commit ad338b82687cec89e662c1d4b8bb5c135e9765f2)
It claims to contain a single bugfix only.
authored by Jörg Thalheim and committed by Vladimír Čunát 52859c48 c6de8f31