lttng-ust: upgrade 2.13.7 -> 2.13.8

Changelog:
============
* Add close_range wrapper to liblttng-ust-fd.so
* ust-tracepoint-event: Add static check of sequences length type
* lttng-ust(3): Fix wrong len_type for sequence
* Fix: libc wrapper: use initial-exec for malloc_nesting TLS

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>