perf data: Don't mention --to-ctf if it's not supported

The option `--to-ctf` is only available when perf has libbabeltrace
support. Hence, on error, we shouldn't state that user must include
`--to-ctf` unless it's supported.

The only user-visible change for this commit is that when `perf` is not
configured to support libbabeltrace, the user is only prompted to
provide the `--to-json` option instead of bothe `--to-json` and
`--to-ctf`.

Signed-off-by: Mahmoud Mandour <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-data.c

···
 		pr_err("You cannot specify both --to-ctf and --to-json.\n");
 		return -1;
 	}
+#ifdef HAVE_LIBBABELTRACE_SUPPORT
 	if (!to_json && !to_ctf) {
 		pr_err("You must specify one of --to-ctf or --to-json.\n");
 		return -1;
 	}
+#else
+	if (!to_json) {
+		pr_err("You must specify --to-json.\n");
+	return -1;
+}
+#endif
 
 	if (to_json)
 		return bt_convert__perf2json(input_name, to_json, &opts);