Build fix: brace-enclosed initlializer lists error with g++ 4.8

Looks like g++ 4.8 is confused by a single argument brace enclosed
initializer list:

utils.hpp: In constructor 'lttng::cli::session_list::session_list(lttng::cli::session_list&&)':
utils.hpp:112:38: error: call of overloaded 'random_access_container_wrapper(<brace-enclosed initializer list>)' is ambiguous
    { std::move(original._container) })
                                      ^

Change-Id: I19da292ed9a49bada7dbda5753bf1bd1442e612f
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>