Add PrefixInformation option struct to parse nduser option.

This is helpful for user space to get the PIO option via netlink message
and check whether the P flag is set or not, this bit flag determines if
we should start DHCPv6 PD process for IPv6 provisioning.

Bug: 315069348
Test: atest NetworkStaticLibTests
Change-Id: Id94b6538c5d88fe43c262ab23c30ccd53c766a62
2 files changed