Update git submodules

* Update docs/submodules/releng from branch 'master'
  to be4cbc60da26dc8ba5e1ae605fbe256f76a94996
  - Update test case exclusions

    netperf has been backported to all active versions.

    Change-Id: I46095db1359ad5a5ecefb529c97b33643bdcdb0e
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 8126d4f..be4cbc6 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 8126d4f36defd96da2511639722fb3b0c4ca0776
+Subproject commit be4cbc60da26dc8ba5e1ae605fbe256f76a94996