lttng-ust: upgrade 2.13.2 -> 2.13.3

Changelog:
==========
* Document ust lock async-signal-safety
* Fix: don't use strerror() from ust lock nocheck
* Fix: remove non-async-signal-safe fflush from ERR()
* Fix: Pointers are rejected by integer element compile time assertion for array and sequence
* Fix: statedump: invalid read during iter_end
* Fix: bytecode interpreter context_get_index() leaves byte order uninitialized

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit d9d7b5d9)
Signed-off-by: Steve Sakoman <steve@sakoman.com>