In my first [try](https://github.com/ziglang/zig/pull/20224) to fix
20212 I didn't reproduce bug on required kernel (6.9.2) and wrongly
concluded that first two completions have different order on newer
kernel.
On my current kernel (6.5.0) order of completions is: send1, recv,
send2. On 6.9.2 order is send1, send2, recv. This fix allows second two
completions to arrive in any order.
Tested on both kernels.
Fixes: #20212