perf tools: Introduce callgraph_set for callgraph option

Introduce callgraph_set to indicate whether the callgraph option was set
by user.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1438162936-59698-4-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index cf459f8..cccb4cf 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -52,6 +52,7 @@
 	bool	     sample_weight;
 	bool	     sample_time;
 	bool	     sample_time_set;
+	bool	     callgraph_set;
 	bool	     period;
 	bool	     sample_intr_regs;
 	bool	     running_time;