dont try to close fd after an error

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Don't leak memory when reading creds in callback

When we grab the creds from a nih_io message, the msg gets
reparented to the new parent we pass in - which was NULL.
So it did not get removed.  Reparent it to our sock data,
so it will get freed when we are done with the scm
transaction.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>