This can cause issues if the circuit was repurposed into a padding circuit
instead of closing, since in that case we will wipe off the rend_data.

This happened when I went to fix long lines after running "make
autostyle".

If "Log debug ..." is not set, the decrement never happens. This lead to the
package/deliver window to be out of sync at the stream level and thus breaking
the connection after 50+ cells.

Fixes #30628



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

When this function was implemented, it counted all the entry guards
in the bridge set.  But this included previously configured bridges,
as well as currently configured ones!  Instead, only count the
_filtered_ bridges (ones that are configured and possibly reachable)
as maybe usable.

Fixes bug 29875; bugfix on 0.3.0.1-alpha.

Otherwise, we won't realize that we haven't got enough bridge
information to build circuits.  Part of a fix for ticket 29875.

For now, only tests HS circuit repurpose function.

Part of #29034

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

This is necessary since shutting down libevent frees some pointer
that the subsystems want to free themselves. A longer term solution
will be to turn the evloop module into a subsystem itself, but for
now it is best to do the minimal fix.

Fixes bug 30629; bugfix on 0.4.1.1-alpha.

Previously, we were looking at our global settings to see what kind
of proxy we had.  But doing this would sometimes give us the wrong
results when we had ClientTransportPlugin configured but we weren't
using it for a particular connection.  In several places in the
code, we had added checks to see if we were _really_ using a PT or
whether we were using a socks proxy, but we had forgotten to do so
in at least once case.  Instead, since every time we call this
function we are asking about a single connection, it is probably
best just to make this function connection-specific.

Fixes bug 29670; bugfix on 0.2.6.2-alpha.

This looks a copy-and-paste error to me.  Fixes bug 30646; bugfix on
0.4.1.1-alpha.