Add missing mutex to qi::log TailFileLogHandler, part II

Change-Id: I8937aaeaaa9ac818538779c9fe047671bff4bbcb
tailfileloghandler: unhide a variable

Change-Id: I589599b95f18faa6d1213428f8c21be52d7a8e8a
Reviewed-on: http://gerrit.aldebaran.lan:8080/11130
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Tested-by: cgestes <gestes@aldebaran-robotics.com>
Add missing mutex to qi::log HeadFileLogHandler

Change-Id: I05f1ac48b12e64576caa5ed2fa9914d9ea5d8a3e
Reviewed-on: http://gerrit.aldebaran.lan:8080/11311
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Tested-by: llec <llec@aldebaran-robotics.com>