Include a line number of the call site.

Add a dummy track parser, that reads through MIDI tracks and events. To make sure we understand the
file structure correctly, no actual tracks or events are generated.

Also add test cases to make sure we read through a MIDI file correctly.

MIDI files aren't RIFF, calling stream_skip_chunk on it is invalid.

Fixes a test that is frequently failing on the GitLab CI.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=56188

The unwind info is now printed from unwind.c.

%gs is not set until call_init_thunk().
Also, adjust other TEB accesses to be consistent with the surrounding
functions.

Fixes a crash on macOS introduced by 7ae488a2
("ntdll: Don't hardcode xstate size in syscall frame.")