selftest: sync: basic tests for sw_sync framework

These tests are based on the libsync test suite from Android.
This commit lays the ground for future tests, as well as includes
tests for a variety of basic allocation commands.

Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>