Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 4b81bb7b15f60b3725c9295aabccb05ab0538e2c
  - Force exit code if failure

    Change-Id: Ia445281018f51ae062b63d2f347ffcc725370971
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 4d4e506..4b81bb7 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 4d4e506895df33159b85999903124d62550bf183
+Subproject commit 4b81bb7b15f60b3725c9295aabccb05ab0538e2c