Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Fix Functest return values"
  - Fix Functest return values

    The current impl doesn't exit as expected when running both tiers and
    testcases [1][2].

    [1] https://build.opnfv.org/ci/view/functest/job/functest-apex-baremetal-daily-master/324/console
    [2] https://build.opnfv.org/ci/view/functest/job/functest-apex-baremetal-daily-fraser/284/console

    Change-Id: I934c3f54313522011ed87ebebe77fbb285b8ab49
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 49f6d35..ac647b0 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 49f6d3509d810fed4cbc15e1b0b86cf1eb8b266e
+Subproject commit ac647b0414bd14615ebd4927a2926b328eaceda1