Add Vendor Class Identifier for dhclient.
Add Vendor Class Identifier for dhclient.

Report ourselves as "PXE UROOT" so we can be distinguished from other
pxe clients. Also always request a subnetmask option rather than only in
the DISCOVER message.

Signed-off-by: Gan Shun Lim <2e7f5e6c120ad45644b6c32fd10bafcf8f554f9f@gmail.com>

u-root/u-root,GanShun/u-root,u-root/u-root,hugelgupf/u-root,hugelgupf/u-root,u-root/u-root,GanShun/u-root,hugelgupf/u-root,hugelgupf/u-root,GanShun/u-root