perf intel-pt: Add default config for pass-through branch enable

Branch tracing is enabled by default, so a fake config bit called 'pt'
(pass-through) was added to allow the 'branch enable' bit to have affect.
Add default config 'pt,branch' which will allow users to disable branch
tracing using 'branch=0' instead of having to specify 'pt,branch=0'.

Signed-off-by: Adrian Hunter <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/arch/x86/util/intel-pt.c

···
 	int psb_cyc, psb_periods, psb_period;
 	int pos = 0;
 	u64 config;
+	char c;
 
 	pos += scnprintf(buf + pos, sizeof(buf) - pos, "tsc");
 
···
 					 ",psb_period=%d", psb_period);
 		}
 	}
+
+	if (perf_pmu__scan_file(intel_pt_pmu, "format/pt", "%c", &c) == 1 &&
+	    perf_pmu__scan_file(intel_pt_pmu, "format/branch", "%c", &c) == 1)
+		pos += scnprintf(buf + pos, sizeof(buf) - pos, ",pt,branch");
 
 	pr_debug2("%s default config: %s\n", intel_pt_pmu->name, buf);