Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=52396
-- v2: ntdll: Use .seh handler in call_unwind_handler() on x64. ntdll/tests: Add test for collided unwind. ntdll: Use .seh handler in call_handler() on x64. ntdll: Set EH_NESTED_CALL flag in call_stack_handlers() on x64.