lttng-libust: bump version to 2.9.0

lttng-libust: bump version to 2.9.0

Drop sha256 hash. The combination of md5 and sha1 hashes is enough.

Add a patch that fixes a build failure due to using the compiler of the
host machine. The patch has been submitted as a pull request:
  https://github.com/lttng/lttng-ust/pull/41

Release notes:
  https://lists.lttng.org/pipermail/lttng-dev/2016-November/026761.html

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>