Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Protect vs exceptions when ext_nets is empty

    Otherwise several exceptions are raised in TestCase constructors
    (those defined in heathcheck).

    Change-Id: I4cb054f7092ea9db02cb8c4469e99848533c556b
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 94fc7e3..e491334 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 94fc7e3d0f904d227e3980567e640e2a4debf917
+Subproject commit e491334942083a81dab0f3450a809e29b0687c31