The net.link.ether.bridge.enable sysctl MIB variable enables bridge

functionality by setting to a non-zero value. This is an integer, but
is treated as a boolean by the code, so clamp it to a boolean value
when set so as to avoid unnecessary bridge reinitialization if it's
changed to another value.

PR:		kern/61174
Requested by:	Bruce Cran

sys/net/bridge.c

@@ -565,6 +565,7 @@ sysctl_bdg(SYSCTL_HANDLER_ARGS)
     int error;
 
     error = sysctl_handle_int(oidp, &enable, 0, req);
+    enable = (enable) ? 1 : 0;
     BDG_LOCK();
     if (enable != do_bridge) {
 	do_bridge = enable;