lttng-tools: improve ptest and test suite

lttng-tools: improve ptest and test suite

Multiple patches are to be applied to improve the current ptest suite.

0001-Fix-tests-link-libpause_consumer-on-liblttng-ctl.patch
0002-Fix-test-skip-test_getcpu_override-on-single-thread-.patch
0003-Fix-test-unit-the-tree-origin-can-be-a-symlink-itsel.patch
0006-Tests-check-for-lttng-modules-presence.patch

All deal with problem in the test suite. Most of these are already
accepted upstream and will be removed on the next recipe update.

0004-Skip-when-testapp-is-not-present.patch

Is a OE specific fix that make sure that we skip the test if
the test util application (event generator) is not present. We are
still unsure on how (upstream) we are going to solve this problem. We
already have this problem if a user build lttng without lttng-ust
(--without-lttng-ust). We will most probably end up splitting each test
into kernel and userspace tests and adjust the makefile accordingly.
Another option is to probe lttng for enabled function at runtime.

0005-Tests-use-modprobe-to-test-for-the-presence-of-lttng.patch

Is a requirement for 0006 that should be accepted upstream shorlty.

0007-Fix-getgrnam-is-not-MT-Safe-use-getgrnam_r.patch

Fixes a race found while testing OE built with musl. This is a legit
bug. The fixes or a variant should be accepted soon.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>