wpa: Address CTRL-EVENT-SCAN-FAILED

Some installations may experience CTRL-EVENT-SCAN-FAILED when
associating to an AP. Installations that specify
ifconfig_wlan0="WPA ... up" in rc.conf do not experience
the problem whereas those which specify ifconfig_wlan0="WPA" without
the "up" will experience CTRL-EVENT-SCAN_FAILED.

However those that specify "up" in ifconfig_wlan0 will be able to
reproduce this problem by service netif stop wlan0;
service netif start wlan0. Interestingly The service netif stop/start
problem is reproducible on the older wpa 2.9 as well.

Reported by:	dhw
Reported by:	"Oleg V. Nauman" <oleg _ theweb_org_ua>
Reported by:	Filipe da Silva Santos <contact _ shiori_com_br>
Reported by:	Jakob Alvermark <jakob _ alvermark_net>
MFC after:	3 days

libexec/rc/rc.d/wpa_supplicant

@@ -12,6 +12,7 @@
 
 name="wpa_supplicant"
 desc="WPA/802.11i Supplicant for wireless network devices"
+start_postcmd="wpa_poststart"
 rcvar=
 
 ifn="$2"
@@ -27,6 +28,10 @@ is_ndis_interface()
 	esac
 }
 
+wpa_poststart() {
+	ifconfig ${ifn} up
+}
+
 if is_wired_interface ${ifn} ; then
 	driver="wired"
 elif is_ndis_interface ${ifn} ; then