Test debug-info

Test debug-info

Add a test program source code, instructions to compile it with the
already compiled libhello library, and provide a lttng-ust trace of this
program running.

The test runs babeltrace on this trace with the
--debug-info-target-prefix option set to the tree of babeltrace which
allows it to find the debug symbols, and we verify that the text output
contains the complete debug_info context structure.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>