syslog: Provide stub functions for openlog and syslog.

syslog: Provide stub functions for openlog and syslog.

One option to implement openlog and syslog functionality in Windows
is to use windows event logger. But it looks like it involves changing
registry settings and in general looks complicated.

For the time being, do nothing for syslog. All the information needed for
debugging will be present through the 'file' option anyways.

We can start OVS daemons on Windows with "-vfile:info -vsyslog:off".

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>