Use `getrandom(2)` system call

Using getrandom system call is faster than reading from /dev/random and doesn't require a file descriptor.

Ubuntu also enables it: https://git.launchpad.net/ubuntu/+source/wpa/tree/debian/config/hostapd/linux?id=dd3cefa946a1fa14c957606bb016af801f7d6d44#n259

added priority3-normal statusunconfirmed labels

assigned to @dvzrv and @spupykin

approved this merge request

merged