perf auxtrace: Add an option to synthesize callchains for regular events

Currently, callchains can be synthesized only for synthesized events. Add
an itrace option to synthesize callchains for regular events.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200401101613.6201-9-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>