Add libcutils_test into TEST_MAPPING

libcutils_test is fixed for all architectures and handles cases when
schedtune and/or cpuset cgroup controllers are not enabled. Include it
into presubmit test list.

Test: ran tests
Change-Id: I294220e18aae5e5760e7e6bdee7a2fe4d9c6d6a4
Signed-off-by: Suren Baghdasaryan <surenb@google.com>