Fix: circular dependency on symbol lttng_id_tracker_lookup

Fix: circular dependency on symbol lttng_id_tracker_lookup

Adding lttng_id_tracker_lookup feature into kprobes, uprobes and
kretprobes introduces a circular dependency between lttng-tracer.ko and
the respective probe modules.

There is no real reason for having the kprobes/uprobes/kretprobes
modules separate from the tracer core, so combine those.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iea80c8054054b341e1836c8675c04e00424608fc