Define O_DIRECTORY with different value

Define O_DIRECTORY with different value

Previous fix regarding confusion between O_NONBLOCK and O_DIRECTORY
values changed O_NONBLOCK to a different number, therefore it drifted
away from FNONBLOCK (for which it was an alias) and caused a blocking
socket.

This commit simply changes the value of O_DIRECTORY, without being
necessary to redefine O_NONBLOCK or FNONBLOCK.

Fixes: 58f9f3a3f7b5 ("include/fcntl.h: Replace O_NONBLOCK with new one
on arm")

Signed-off-by: Maria Sfiraiala <maria.sfiraiala@gmail.com>
Reviewed-by: Sergiu Moga <sergiu.moga@protonmail.com>
Reviewed-by: Simon Kuenzer <simon@unikraft.io>
Reviewed-by: Razvan Deaconescu <razvan.deaconescu@cs.pub.ro>
Approved-by: Razvan Deaconescu <razvan.deaconescu@cs.pub.ro>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #21