ss_add_info_dir: fix error handling when memory allocation fails

ss_add_info_dir: fix error handling when memory allocation fails

If the realloc() and malloc() calls fail, avoid a memory leak as well
as a potential seg fault.

[ Fix error code setting to avoid depending on malloc() and realloc()
  setting errno. -- TYT ]

Signed-off-by: Wu Guanghao <wuguanghao3@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Reviewed-by: Wu Bo <wubo40@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>