Fix: auto load session in the auto/ directory

The session daemon will now automatically load sessions from the auto/
directory in the session config path. Both system config path and home
config path are used. The session is only loaded if the UID of the
session file matches the UID of the session daemon (or root).

For that, a autoload parameter has been added to the
config_load_session() function to indicate that we want to auto load
sessions.

Fixes #812

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: add missing URCU_TLS to logging time variable

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: static array larger than necessary

The longest string that can be returned should be 20 chars long, as per
the comment.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: check malloc return value

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: memory leak in lttng_enable_event_with_exclusions

lttng_enable_event_with_exclusions leaks a filter expression when
automatically generated filter statements are used. This happens when
loglevel and logger name filtering are used when enabling JUL events.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: refactor function that fixes memory leak also

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: logger name dropped from filter condition when loglevels are used

This fix ensures that the loglevel expression is appended to the filter
expression and does not overwrite the current one.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>