Log info on ancient one-hop circuits in heartbeat

This is an attempt to diagnose 8387.
Remove /tor/dbg-stability.txt URL.

The /tor/dbg-stability.txt URL was meant to help debug WFU and MTBF
calculations, but nobody was using it.

Fixes #11742.
Don't start sandbox except for CMD_RUN_TOR

This was crashing on --verify-config in the debian startup script, if you
had sandboxing enabled.  Fixes 11609; fix on 0.2.5.1-alpha.
Consensus method 18: Add a base64 ID digest to the microdesc

This is a stopgap measure to make sure that microdescriptors never
collide; see bug 11743.
Fix cross-compiling when 128-bit math compiles but won't link

Apparently, there exist cross-compiling environments for arm7 where
you can compile a 64x64->128 multiply, but not link it.

Fixes bug 11729; bugfix on 0.2.4.8-alpha. Patch from 'conradev'.
Use siphash on channel/circuit-id map too

Fixes ticket 11750.
Fix compilation with DEBUG_DNS_CACHE

Reported by cypherpunks.

Fix for #11761; bugfix on 0.2.3.13-alpha where we made ht.h stop using
_identifiers.
Faster chan_circid_entry_hash implementation

Since this is critical-path, let's tune the value we pass to
csiphash a little so it fits into one whole round.
Add a siphash benchmark.
Check HT_REP_IS_BAD_() when giving a bug-7164 warning.

This may let us know if we're hitting 7164 because of an
hte_hash-corruption situation proposed by "cypherpunks" in bug
11737.
Merge remote-tracking branch 'karsten/bug11742'
changes file for bug11743
fix a copy-paste comment mistake
Future-proof "id" lines against proposal 220.
Unit test for write_to_buf_zlib
Unit test for dirvote_create_microdescriptor
Merge branch 'bug11743_option_b'
Merge remote-tracking branch 'public/bug11750'
Remove a spurious variable.
Split portfw-error-logging code into a new function.

No code has changed; only moved. Part of a fix for 9781.