fixup! Print thread ID in panic message if thread name is unknown

Author: tgross35

tests/rustdoc-ui/doctest/failed-doctest-output-windows.stdout

@@ -27,7 +27,7 @@ stderr:
 stderr 1
 stderr 2
 
-thread 'main' panicked at $DIR/failed-doctest-output-windows.rs:7:1:
+thread 'main' ($TID) panicked at $DIR/failed-doctest-output-windows.rs:7:1:
 oh no
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace