Merge #20507: sync: print proper lock order location when double lock is detected
db058efeb0821cb5022e3b29e0aff3627d7aaf83 sync: use HasReason() in double lock tests (Vasil Dimov)
a21dc469ccf076ca3b07b1adbd8bf667145f1c44 sync: const-qualify the argument of double_lock_detected() (Vasil Dimov)
6d3689fcf6cff397187028344570489db3e6ecf4 sync: print proper lock order location when double lock is detected (Vasil Dimov)
Pull request description:
Before:
```
Assertion failed: detected double lock at src/sync.cpp:153, details in debug log.
```
After:
```
Assertion failed: detected double lock for 'm' in src/test/sync_tests.cpp:40 (in thread ''), details in debug log.
```
ACKs for top commit:
jonasschnelli:
utACK db058efeb0821cb5022e3b29e0aff3627d7aaf83
ajtowns:
ACK db058efeb0821cb5022e3b29e0aff3627d7aaf83
hebasto:
ACK db058efeb0821cb5022e3b29e0aff3627d7aaf83, tested on Linux Mint 20 (x86_64).
Tree-SHA512: 452ddb9a14e44bb174135b39f2219c76eadbb8a6c0e80d64a25f995780d6dbc7b570d9902616db94dbfabaee197b5828ba3475171a68240ac0958fb203a7acdb
