perf inject: Fix missing free in copy_kcore_dir()

Free string allocated by asprintf().

Fixes: d8fc085 ("perf inject: Keep a copy of kcore_dir")
Signed-off-by: Adrian Hunter <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: ahunter6

tools/perf/builtin-inject.c

@@ -891,7 +891,9 @@ static int copy_kcore_dir(struct perf_inject *inject)
 	if (ret < 0)
 		return ret;
 	pr_debug("%s\n", cmd);
-	return system(cmd);
+	ret = system(cmd);
+	free(cmd);
+	return ret;
 }
 
 static int output_fd(struct perf_inject *inject)