route-table-bsd: Stop caching pid

The cache here doesn't work anymore as the recent
commit b772066ffd066d59d9ebce092f6665150723d2ad
("route-table: Remove Unregister.")
made this function called before daemonizing,
thus with a different pid.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Ben Pfaff <blp@nicira.com>
ovs-router: non-Linux support

Refactor ovs-router so that it can work with non-Linux platforms
at least in some extent, using the existing route-table code as
a fallback.  Known restriction: for such platforms, "ovs/router/show"
command does not show "Cached" kernel routes.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
route-table-bsd: Provide gateway info

For userspace tunneling.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Ben Pfaff <blp@nicira.com>
route-table-bsd: Add some DBG logs

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Ben Pfaff <blp@nicira.com>