selinux: fix problems in netnode when BUG() is compiled out

When the BUG() macro is disabled at compile time it can cause some
problems in the SELinux netnode code: invalid return codes and
uninitialized variables.  This patch fixes this by making sure we take
some corrective action after the BUG() macro.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>