aio: use proper barriers in socket closure code

sch: introduce Start/IsEmpty/WaitEmpty/Stop()

sch: use InterruptibleMutex in it

box: introduce InterruptibleMutex

box: introduce bitwise atomic operations

sch: remove 'retry' from the scheduler

sch: don't receive front signal all the time

bench: one another io_uring slowdown case

readme: use relative GitHub links

ci: relax UnitTestThreadLocalPoolStress

ci: introduce Linux ARM testing

readme: bring it up to date

example: fix a few nitpicks

ci: introduce examples testing

example: introduce examples