server: Log closure before sending it

This seems foolishly cosmetic on the surface - and will reorder log
messages in certain failure cases.  "request could not be marshalled"
will now appear after logging the request that failed to marshal
instead of before.

The real point of this is that a follow up patch will make
wl_closure_send() set fds to -1 as it buffers them for send, so
they can be more easily cleaned up.

Doing that while leaving this order unchanged would result in
printing -1 for fds instead of their value.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>