It turns out that STAP_PROBEV() is not available on FreeBSD thus having
sdt/sdt.h is not enough. Look for it now at configure time.

Closes #40174

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

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

Fixes #40173

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

Fixes #40177; bugfix on 0.4.5.1-alpha.

Fix bug where running a relay on Windows would use 100% CPU
after some time. Makes Windows >= Vista the required Windows
version to build and run tor.

Fixes #40171. Bug not in any released Tor.

It was deprecated 0.3.1.1-alpha.

According to #22473, nothing uses it.

Closes #22473.

These options are meant for testing builds only, and are likely to
cause trouble if used in a production environment.

Closes #18888.

OpenSSL doesn't seem to report error locations in the same way as
before, which broke one of our tests.

Fixes bug 40170; bugfix on 0.2.8.1-alpha.

Apparently it conflicts with definitions elsewhere in Openssl 3.0.0.

We can't do this in the C headers, since by the time we include
`opensslv.h` in order to check the openssl version number, we will
have included `openssl/macros.h`, which is the thing that checks
whether we disabled deprecation warnings.

The "engines.h" header has lots of stuff; the "opensslv.h" header
has the version number, which is all we actually need here.

We need to do this because we're about to change this header to
conditionally define OPENSSL_SUPPRESS_DEPRECATED, and it would be
too late to do so if we'd already included "engines.h".

The loop in the earlier patch would invoke undefined behavior in two
ways: First, it would check whether it was looking at a space before
it checked whether the pointer was in-range.  Second, it would let a
pointer reach a position _before_ the start of a string, which is
not allowed.

I've removed the assertion about empty messages: empty messages can
be their own warning IMO.

I've also added tests for this formatting code, to make sure it
actually works.