Several BGP channel options (including 'next hop self') could be
reconfigured without session reset, with just route refeed/refresh.
The patch improves reconfiguration code to do it that way.

The 'deterministic med' option is implemented by suppressing other than
best-in-group routes (grouped by ASN) from best route selection. This
interferes with 'merge paths' as supressed routes are no longer mergable
with best route. This is fixed by suppressing only those routes that are
not mergable with best-in-group route.

 - add -flto only to default CFLAGS
 - add -fno-strict-aliasing, -fno-strict-overflow always
 - remove -Wno-implicit-fallthrough

The command initiating planned graceful restart including bird shutdown
should be called 'graceful restart' instead of 'graceful down', as the
later should be reserved for graceful shutdown in style of RFC 8326.

The formatting was broken due to longer date in 'since' column.

Protocol can have specified VRF, in such case it is restricted to a set
of ifaces associated with the VRF, otherwise it can use all interfaces.

The patch allows to specify VRF as 'default', in which case it is
restricted to a set of iface not associated with any VRF.

The formatting was broken when too short router-id was used.

Includes patch from Maximilian Eschenbacher

Mismatched types to printf(). The old code coincidentally worked on amd64
due to its calling conventions.

Thanks to Maximilian Eschenbacher for the bugreport.

Allow multiple BFD instances in separate VRFs, dispatch BFD requests
according to VRFs.

Thanks to Alexander Zubkov for notice and patches.

Use route replace netlink op instead of delete+add netlink ops for kernel
IPv4 route replace. This avoids some packetloss during route replace.
Still use the old behavior for IPv6, as some kernel bugs are hidden in
IPv6 ECMP handling.

Per RFC 3101, N-bit signalling NSSA support should be used only in Hello
packets, not in DBDES packets. BIRD since 2.0.4 verifies N-bit in
neighbor structure, which is learned from DBDES packets, therefore
NSSA-LSAs are not propagated to proper implementations of RFC 3101.

This patch fixes that. Both removing the check and removing N-bit from
DBDES packet. This will fix compatibility issues with proper
implementations, but causes compatibility issues with BIRD 2.0.4.

This led in corner cases to undefined buffer content
and garbage output.

Most LSA origination is blocked in ospf_update_topology(), this fix
blocks LSA origination from ospf_rt_spf().