When we lose a route and have no feasible alternate, we should send requests
straight away rather than waiting for a periodic update.  If we have an
unfeasible route, send according to that route and resend, otherwise do
a multicast.

Reported by janus.

This also removes special casing of late Hellos.

- Hello is not ignored if there is a mandatory sub-TLV,
- non-wildcard Updates also,
- Duplicated check for Requests,
- wrong size for the beginning of sub-TLVs for Seqno Requests,
- wrong size for source specific Requests and Seqno Requests.

That patch was fixing a little bug, but makes another bigger one.
The previous patch fixes both.

This reverts commit e687a58f.

Quiet git more.

Share the data better.

route.c was the only routine in all of babeld that had tabs creep in.

ignore core gmon.out and cscope.out

I took the "const" inside disambiguation.c as definitive.

In order to address this, this patch removes the <linux/if_bridge.h>
inclusion, and instead defines BRCTL_GET_BRIDGES to the appropriate
value if it's not provided by the C library.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>