wifi: clear WiFi requested_scan if suppl goes INACTIVE

It's possible for wpa_supplicant to transition to INACTIVE
state with an outstanding requested_scan pending.  This can
lead to a stall condition where scanning no longer occurs.

[thaller@redhat.com: added break statement to avoid fall-through]

https://mail.gnome.org/archives/networkmanager-list/2016-June/msg00116.html

src/devices/wifi/nm-device-wifi.c

@@ -1954,6 +1954,11 @@ supplicant_iface_state_cb (NMSupplicantInterface *iface,
 		else
 			_LOGI (LOGD_DEVICE | LOGD_WIFI, "supplicant interface keeps failing, giving up");
 		break;
+	case NM_SUPPLICANT_INTERFACE_STATE_INACTIVE:
+		priv->requested_scan = FALSE;
+		nm_clear_g_source (&priv->pending_scan_id);
+		request_wireless_scan (self, NULL);
+		break;
 	default:
 		break;
 	}