uv_fs_close on an unexisting stream doesn't return an error

[csaoh]

Looks like uv_fs_close always returns the initial stream, even when this stream doesn't exist and close fails.

For example,

uv_fs_close($loop, 42, function ($result){});

returns 42

uv_fs_close($loop, 0, function ($result){});

returns 0, and so on.