lib: turn INT_FLAG_REG_RING into masked flag If INT_FLAG_REG_RING matches IORING_ENTER_REGISTERED_RING, then it's possible to drop the branches around masking in this value for every io_uring_enter(2) system call. This also allows for doing the same with future flags, where it would be beneficial to have them set for each invocation, without needing to add branches for that. Signed-off-by: Jens Axboe <[email protected]>