hostapd: Global control interface notifications

This commit implements hostapd global control interface notifications
infrastructure. hostapd global control interface clients issue
ATTACH/DETACH commands to register and deregister with hostapd
correspondingly - the same way as for any other hostapd/wpa_supplicant
control interface.

Bug: 24270573

Change-Id: I46da39e8262a446e7779a1adfbcb08b5bfa382d7
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
diff --git a/src/ap/hostapd.h b/src/ap/hostapd.h
index be5c7a8..dc71694 100644
--- a/src/ap/hostapd.h
+++ b/src/ap/hostapd.h
@@ -41,6 +41,7 @@
 
 	size_t count;
 	int global_ctrl_sock;
+	struct wpa_ctrl_dst *global_ctrl_dst;
 	char *global_iface_path;
 	char *global_iface_name;
 #ifndef CONFIG_NATIVE_WINDOWS