perf auxtrace: Add itrace d+o option to direct debug log to stdout

It can be useful to see debug output in between normal output.

Add 'o' to the flags of debug option 'd', so that '--itrace=d+o' can
specify output of the debug log to stdout.
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20211027080334.365596-6-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/itrace.txt

@@ -62,5 +62,6 @@
 	debug messages will or will not be logged. Each flag must be preceded
 	by either '+' or '-'. The flags are:
 		a	all perf events
+		o	output to stdout
 
 	If supported, the 'q' option may be repeated to increase the effect.

tools/perf/util/auxtrace.h

@@ -59,6 +59,7 @@ enum itrace_period_type {
 #define AUXTRACE_ERR_FLG_DATA_LOST	(1 << ('l' - 'a'))
 
 #define AUXTRACE_LOG_FLG_ALL_PERF_EVTS	(1 << ('a' - 'a'))
+#define AUXTRACE_LOG_FLG_USE_STDOUT	(1 << ('o' - 'a'))
 
 /**
  * struct itrace_synth_opts - AUX area tracing synthesis options.
@@ -641,6 +642,7 @@ bool auxtrace__evsel_is_auxtrace(struct perf_session *session,
 "				d[flags]:		create a debug log\n" \
 "							each flag must be preceded by + or -\n" \
 "							log flags are: a (all perf events)\n" \
+"							               o (output to stdout)\n" \
 "				f:	    		synthesize first level cache events\n" \
 "				m:	    		synthesize last level cache events\n" \
 "				t:	    		synthesize TLB events\n" \