These won't/shouldn't ever be called from C, so there's no reason to
preserve naming.

Allows an optional no-op for testing purposes

"ours" to avoid version bump.

Using tt_assert in these helpers was implying to scan-build that our
'new' functions might be returning NULL, which in turn would make it
warn about null-pointer use.

"ours" merge to avoid version bump.

This would only show up on systems like windows where monotime_t and
monotime_coarse_t are different types.

This way it will match the insert queue in 029 and later.

We've been seeing problems with destroy cells queues taking up a
huge amount of RAM.  We can mitigate this, since while a full packed
destroy cell takes 514 bytes, we only need 5 bytes to remember a
circuit ID and a reason.

Fixes bug 24666. Bugfix on 0.2.5.1-alpha, when destroy cell queues
were introduced.

With extra_space negative, it means that the "notsent" queue is quite large so
we must consider that value with the current computed tcp_space. If we end up
to have negative space, we should not add more data to the kernel since the
notsent queue is just too filled up.

Fixes #24665

Signed-off-by: David Goulet <dgoulet@torproject.org>

Spotted by coverity scan as 1426749 and 1426750

Bug not in any released Tor.