Revert mmap2

upstream commits 3090ffb5a2515 and 2fd869f08aec

Signed-off-by: David Ahern <dsahern@gmail.com>
perf sched timehist: Add summary and summary only options

Revert show_events option in favor of consistency with perf-trace.

Signed-off-by: David Ahern <dsahern@gmail.com>