perf inject: Set branch stack feature flag when synthesizing branch stacks

The branch stack feature flag is set by 'perf record' when recording
data that contains branch stacks.  Consequently, when 'perf inject'
synthesizes branch stacks, the feature flag should be set also.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1443186956-18718-13-git-send-email-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-inject.c

@@ -537,9 +537,13 @@ static int __cmd_inject(struct perf_inject *inject)
 		 * The AUX areas have been removed and replaced with
 		 * synthesized hardware events, so clear the feature flag.
 		 */
-		if (inject->itrace_synth_opts.set)
+		if (inject->itrace_synth_opts.set) {
 			perf_header__clear_feat(&session->header,
 						HEADER_AUXTRACE);
+			if (inject->itrace_synth_opts.last_branch)
+				perf_header__set_feat(&session->header,
+						      HEADER_BRANCH_STACK);
+		}
 		session->header.data_offset = output_data_offset;
 		session->header.data_size = inject->bytes_written;
 		perf_session__write_header(session, session->evlist, fd, true);