DataAligner: fix incorrect return value
DataAligner: fix incorrect return value

Case:
create aligner with alignment=40

call Align(20)
buffer size became 20
return 20

call Align(20)
buffer size became 40
consume whole buffer
it returns 40
cancel token
check token and return 40

BUT must return 20 i.e. amount of data added to buffer

GSGroup/stingraykit,GSGroup/stingraykit