Merge branch 'RTO_ONLINK'

Guillaume Nault says:

====================
ipv4: Remove RTO_ONLINK from udp, ping and raw sockets.

udp_sendmsg(), ping_v4_sendmsg() and raw_sendmsg() use similar patterns
for restricting their route lookup to on-link hosts. Although they use
slightly different code, they all use RTO_ONLINK to override the least
significant bit of their tos value.

RTO_ONLINK is used to restrict the route scope even when the scope is
set to RT_SCOPE_UNIVERSE. Therefore it isn't necessary: we can properly
set the scope to RT_SCOPE_LINK instead.

Removing RTO_ONLINK will allow to convert .flowi4_tos to dscp_t in the
future, thus allowing to properly separate the DSCP from the ECN bits
in the networking stack.

This patch series defines a common helper to figure out what's the
scope of the route lookup. This unifies the way udp, ping and raw
sockets get their routing scope and removes their dependency on
RTO_ONLINK.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>