spsc_queue: Relax memory ordering

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
test/spsc_queue: Synchronize threads before starting

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
Add single producer, multiple consumers lock-free queue

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
mpsc_queue: Make unlock_blocks() static

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
test/mpsc_queue: Remove unnecessary include

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>