perf probe: Free string returned by synthesize_perf_probe_point() on failure in synthesize_perf_probe_command()

Building perf with EXTRA_CFLAGS="-fsanitize=address" a leak was detected
elsewhere and lead to an audit, where we found that
synthesize_perf_probe_command() may leak synthesize_perf_probe_point()
return on failure, fix it.

Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/probe-event.c

···
 			goto out;
 
 	tmp = synthesize_perf_probe_point(&pev->point);
-	if (!tmp || strbuf_addstr(&buf, tmp) < 0)
+	if (!tmp || strbuf_addstr(&buf, tmp) < 0) {
+		free(tmp);
 		goto out;
+	}
 	free(tmp);
 
 	for (i = 0; i < pev->nargs; i++) {
 		tmp = synthesize_perf_probe_arg(pev->args + i);
-		if (!tmp || strbuf_addf(&buf, " %s", tmp) < 0)
+		if (!tmp || strbuf_addf(&buf, " %s", tmp) < 0) {
+			free(tmp);
 			goto out;
+		}
 		free(tmp);
 	}