VOL-5155 - triage failure in periodic-voltha-test-bbsim-2.12

.gitignore
----------
  o Ignore a.out and archives/ created late by the test target.

config.mk
makefiles/targets/sterile.mk
makefiles/targets/tox.mk
----------------------------
  o Update sterile target to remove the archives directory.
  o tox.mk updated to remove generated .tox/ directory.

jjb/pipeline/voltha/master/bbsim-tests.groovy
jjb/pipeline/voltha/voltha-2.12/bbsim-tests.groovy
--------------------------------------------------
  o Fixed a typo in the 'Combine and compress' banner.
  o In compress combined log block:
    - Display logs to compress.
    - '|| true' removed from gzip.  Wrap call with log collection
      and only invoke when logs are available (allow cmds to fail on err).

Change-Id: I141c0bbd1e8c946c652f00f21401bd897d8a4135
diff --git a/config.mk b/config.mk
index 3cec7fd..849bd73 100644
--- a/config.mk
+++ b/config.mk
@@ -125,6 +125,16 @@
 
 onf-excl-dirs := $(sort $(strip $(onf-excl-dirs)))
 
+# --------------------------------------------------------------------
+# Repository specific values
+# --------------------------------------------------------------------
+sterile-dirs += archives
+
+# submodules
+# sterile-dirs += global-jjb
+# sterile-dirs += lf-ansible
+# sterile-dirs += packer
+
 # [TODO]#
 #  --------------------------------------------------------------------
 #   o two distinct makefiles/ directories are needed, one for onf-make