Revert certain x86-related changes from #4677. In particular, we avoid restoring the arithmetic flags and (if used) the scratch register before the call to hit_instr_count_threshold, which might not return.
This fix is necessary but it seems to be causing failures in drcachesim.delay-global and drcacheoff.max-global on x86-64 CI testing. These failures are not reproducible outside CI testing and are (so far) inexplicable based on manual analysis of the instrumented assembly code (see https://github.com/DynamoRIO/dynamorio/issues/4711#issuecomment-774776247).
Thus, we are leaving x86_64 as technically broken to keep our tests green until the source of instability is found.
Issue: #4711 (closed)