we can avoid thundering-herd/resonance phenomena when we have multiple
waiters.

Spotted by fgs.

Also req_flags.h was originally made in 2015, not 2014.

Various other cleanups while here.

There are a couple of central things I do not understand about how
this works, if anybody has epoll(2) clue, please contact me.

Copyright statement is updated according to the year of the
last non-trivial change to the file.

This adds a minor change I by mistake added to a merge
commit in an 4.0 commit. (12a6d79c)

When the first backend connection fails (likely because of timeout
from the backend) we ditch the rest of the list.

Fixes #1650

internal matter in cache_backend_*

of the job of setting htc->fd.

just do that from the start.

Remove extra newlines, add tabs and ending punctuation.

While here display the right VCL name if -v is used and the VCL is
not found.

a backend by weight.

This removes the bias problems the current code exhibits when there is
a sick backend in the set.

Spotted by: xcir

Fixes: #1658

to allocate it as part of the "real" structure owning the fd.