Adds two new files generated by raw2trace, each containing 4-entry records of <tid, timestamp, cpuid, instr_count>. These are used to take a global or per-cpu target instruction count and determine the corresponding instruction count within each software thread, for seeking within each trace file. One file is globally sorted by timestamp, and the other is a zip file with a separate component for each cpuid holding entries sorted by timestamp for that cpu.
Adds new invariant_checker tests for each file by passing them in for test_mode. The invariant_checker re-constructs the same sorted sequences using the trace data and confirms it matches the data in the files. This involves adding a new zipfile_stream_t interface for a simple continuous stream of each zipfile component in turn.
Issue: #5538