perf script: Add 'synth' field for synthesized event payloads

Add a field to display the content the raw_data of a synthesized event.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1495786658-18063-22-git-send-email-adrian.hunter@intel.com
[ Resolved conflict with 106dacd86f ("perf script: Support -F brstackoff,dso") ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-script.txt

@@ -117,7 +117,8 @@ OPTIONS
         Comma separated list of fields to print. Options are:
         comm, tid, pid, time, cpu, event, trace, ip, sym, dso, addr, symoff,
         srcline, period, iregs, brstack, brstacksym, flags, bpf-output, brstackinsn, brstackoff,
-        callindent, insn, insnlen. Field list can be prepended with the type, trace, sw or hw,
+        callindent, insn, insnlen, synth.
+        Field list can be prepended with the type, trace, sw or hw,
         to indicate to which event type the field list applies.
         e.g., -F sw:comm,tid,time,ip,sym  and -F trace:time,cpu,trace
 
@@ -193,6 +194,9 @@ OPTIONS
 	instruction bytes and the instruction length of the current
 	instruction.
 
+	The synth field is used by synthesized events which may be created when
+	Instruction Trace decoding.
+
 	Finally, a user may not set fields to none for all event types.
 	i.e., -F "" is not allowed.