Tests: Add Python test_utils module

Basic Python test framework based on the lttng-tools Python bindings
that facilitates the creation of a tracing session saving its trace in
a temporary location, the activation of events in the UST domain and
clean teardown of the test session.

Also provide basic TAP output facilities.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Tests: Add "linking" ust regression test

Based on the "demo" test formerly part of lttng-ust.
Tests userspace tracing with directly, statically and dynamically linked
providers. Also meant as an exemple of building and tracing an application
with all types of provider linking.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Tests: Add "daemon" ust regression test

Based on the "daemon" test formerly part of lttng-ust.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Tests: Add "exit-fast" ust regression test

Based on the "exit-fast" test formerly part of lttng-ust.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Tests: Add "fork" ust regression test

Based on the "fork" test formerly part of lttng-ust.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Tests: Add "libc-wrapper" ust regression test

Based on the "test-libustinstr-malloc" test formerly part of lttng-ust.

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