Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Add tox support

    be easier to test jjb locally before submit for review.
    add unitest in modules dir to tox(tox -emodules)

    Change-Id: Ief4f10debc567d1d3ba111685c86b812a2058697
    Signed-off-by: Julien <zhang.jun3g@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index ac3f798..cec072a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit ac3f798b30ba5d8dcd13b41b309c530dd68ff520
+Subproject commit cec072a7346f75c2670dfa44c8305f7b7841fe67