runtime/trace: test detection of broken timestamps
On some processors cputicks (used to generate trace timestamps)
produce non-monotonic timestamps. It is important that the parser
distinguishes logically inconsistent traces (e.g. missing, excessive
or misordered events) from broken timestamps. The former is a bug
in tracer, the latter is a machine issue.
Test that (1) parser does not return a logical error in case of
broken timestamps and (2) broken timestamps are eventually detected
and reported.