perf evsel: Check if callchain is enabled before setting it up

The construct:

	if (callchain_param)
		perf_evsel__config_callchain(evsel, opts, &callchain_param);

happens in several places, so make perf_evsel__config_callchain() work
just like free(NULL), do nothing if param->enabled is not set.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hendrick Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ykk0qzxnxwx3o611ctjnmxav@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evsel.c

@@ -651,9 +651,9 @@ int perf_evsel__group_desc(struct perf_evsel *evsel, char *buf, size_t size)
 	return ret;
 }
 
-void perf_evsel__config_callchain(struct perf_evsel *evsel,
-				  struct record_opts *opts,
-				  struct callchain_param *param)
+static void __perf_evsel__config_callchain(struct perf_evsel *evsel,
+					   struct record_opts *opts,
+					   struct callchain_param *param)
 {
 	bool function = perf_evsel__is_function_event(evsel);
 	struct perf_event_attr *attr = &evsel->attr;
@@ -699,6 +699,14 @@ void perf_evsel__config_callchain(struct perf_evsel *evsel,
 	}
 }
 
+void perf_evsel__config_callchain(struct perf_evsel *evsel,
+				  struct record_opts *opts,
+				  struct callchain_param *param)
+{
+	if (param->enabled)
+		return __perf_evsel__config_callchain(evsel, opts, param);
+}
+
 static void
 perf_evsel__reset_callgraph(struct perf_evsel *evsel,
 			    struct callchain_param *param)