Fixes bug 31374; bugfix on 0.2.9.1-alpha.

My previous fix removed a comparison, which would have caused us to
warn about every skew instead of skews of over an hour.

Merge changed chutney and stem script lines from 29280 with changed
stem script lines from 30591.

Merge rust additions in 0.3.5 with sudo deletions in 0.2.9.

On some windows builds, time_t is 64 bits but long is not.  This is
causing appveyor builds to fail.

Also, one of our uses of labs() on time_t was logically incorrect:
it was telling us to accept NETINFO cells up to three minutes
_before_ the message they were responding to, which doesn't make
sense.

This patch adds a time_abs() function that we should eventually move
to intmath.h or something.  For now, though, it will make merges
easier to have it file-local in channeltls.c.

Fixes bug 31343; bugfix on 0.2.4.4-alpha.

And add some comments about stem

Part of 29280.

Linux is the first item in the os matrix, so we don't need to specify
it under matrix: include: .

Part of 29280.

Part of 29280.

Part of 29280.

Also filter out stem's SocketClosed logs, and fix some nearby comments.

Part of 30591.

Replace the 157 fallbacks originally introduced in Tor 0.3.5.6-rc
in December 2018 (of which ~122 were still functional), with a
list of 148 fallbacks (70 new, 78 existing, 79 removed) generated
in June 2019.

Closes ticket 28795.

Note that we created extra lists from DE and US, but they didn't add
any more fallbacks when we tried to merge them.

Update the fallback directory mirrors by merging the current list with:
fallback_dirs_2019-06-28-08-58-39_AU_f0437a39ddbc8459.inc

Part of 28795, see that ticket for logs.

Update the fallback directory mirrors by replacing the old list with:
fallback_dirs_2019-06-25-11-49-10_AU_a37adb956fbb5cd2.inc

Part of 28795, see that ticket for logs.

And fix some nearby comments.

Part of 30591.

Previously we had "make check" launched whenever DISTCHECK was
false.  Now we'd like to turn it off in a few other circumstances,
like running chutney.  Maybe stem too?

Skip test_rebind when the TOR_SKIP_TEST_REBIND environmental variable
is set.

Skip test_rebind on macOS in Travis builds, because it is unreliable
on macOS on Travis.

Fixes bug 30713; bugfix on 0.3.5.1-alpha.

Allow the test-stem job to fail in Travis, because it sometimes hangs.

Fixes bug 30744; bugfix on 0.3.5.4-alpha.

Closes ticket 30694.

In Travis, make stem log a controller trace to the console.
And tail stem's tor log after failure.

Closes ticket 30591.