gdbus: explicitly compare pointers to NULL

This patch was generated by the following semantic patch
(http://coccinelle.lip6.fr/)

// <smpl>
@fix disable is_null,isnt_null1@
expression *E;
@@

- !E
+ E == NULL
// </smpl>
diff --git a/gdbus/object.c b/gdbus/object.c
index cc3c5da..d881c58 100644
--- a/gdbus/object.c
+++ b/gdbus/object.c
@@ -201,12 +201,12 @@
 		return NULL;
 	}
 
-	if (!data->introspect)
+	if (data->introspect == NULL)
 		generate_introspection_xml(connection, data,
 						dbus_message_get_path(message));
 
 	reply = dbus_message_new_method_return(message);
-	if (!reply)
+	if (reply == NULL)
 		return NULL;
 
 	dbus_message_append_args(reply, DBUS_TYPE_STRING, &data->introspect,
@@ -405,7 +405,7 @@
 {
 	GSList *list;
 
-	if (!name)
+	if (name == NULL)
 		return NULL;
 
 	for (list = interfaces; list; list = list->next) {
@@ -428,7 +428,7 @@
 	interface = dbus_message_get_interface(message);
 
 	iface = find_interface(data->interfaces, interface);
-	if (!iface)
+	if (iface == NULL)
 		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 
 	for (method = iface->methods; method &&
@@ -464,7 +464,7 @@
 
 	parent_path = g_strdup(child_path);
 	slash = strrchr(parent_path, '/');
-	if (!slash)
+	if (slash == NULL)
 		goto done;
 
 	if (slash == parent_path && parent_path[1] != '\0')
@@ -481,7 +481,7 @@
 		goto done;
 	}
 
-	if (!data)
+	if (data == NULL)
 		goto done;
 
 	g_free(data->introspect);
@@ -554,7 +554,7 @@
 	struct interface_data *iface;
 
 	iface = find_interface(data->interfaces, name);
-	if (!iface)
+	if (iface == NULL)
 		return FALSE;
 
 	data->interfaces = g_slist_remove(data->interfaces, iface);
@@ -601,14 +601,14 @@
 
 	*args = NULL;
 	if (!dbus_connection_get_object_path_data(conn, path,
-					(void *) &data) || !data) {
+					(void *) &data) || data == NULL) {
 		error("dbus_connection_emit_signal: path %s isn't registered",
 				path);
 		return FALSE;
 	}
 
 	iface = find_interface(data->interfaces, interface);
-	if (!iface) {
+	if (iface == NULL) {
 		error("dbus_connection_emit_signal: %s does not implement %s",
 				path, interface);
 		return FALSE;
@@ -621,7 +621,7 @@
 		}
 	}
 
-	if (!*args) {
+	if (*args == NULL) {
 		error("No signal named %s on interface %s", name, interface);
 		return FALSE;
 	}
@@ -644,7 +644,7 @@
 		return FALSE;
 
 	signal = dbus_message_new_signal(path, interface, name);
-	if (!signal) {
+	if (signal == NULL) {
 		error("Unable to allocate new %s.%s signal", interface,  name);
 		return FALSE;
 	}
@@ -702,7 +702,7 @@
 {
 	struct generic_data *data = NULL;
 
-	if (!path)
+	if (path == NULL)
 		return FALSE;
 
 	if (dbus_connection_get_object_path_data(connection, path,
diff --git a/gdbus/polkit.c b/gdbus/polkit.c
index ed876ca..aef5075 100644
--- a/gdbus/polkit.c
+++ b/gdbus/polkit.c
@@ -163,7 +163,7 @@
 
 	msg = dbus_message_new_method_call(AUTHORITY_DBUS, AUTHORITY_PATH,
 				AUTHORITY_INTF, "CheckAuthorization");
-	if (!msg) {
+	if (msg == NULL) {
 		dbus_free(data);
 		return -ENOMEM;
 	}
diff --git a/gdbus/watch.c b/gdbus/watch.c
index c0dcc93..e7c203a 100644
--- a/gdbus/watch.c
+++ b/gdbus/watch.c
@@ -204,8 +204,7 @@
 	struct filter_data *data;
 	const char *name = NULL, *owner = NULL;
 
-	if (!filter_data_find(connection, NULL, NULL, NULL, NULL, NULL,
-				NULL)) {
+	if (filter_data_find(connection, NULL, NULL, NULL, NULL, NULL, NULL) == NULL) {
 		if (!dbus_connection_add_filter(connection,
 					message_filter, NULL, NULL)) {
 			error("dbus_connection_add_filter() failed");
@@ -382,7 +381,7 @@
 	/* Remove filter if there are no listeners left for the connection */
 	data = filter_data_find(connection, NULL, NULL, NULL, NULL, NULL,
 					NULL);
-	if (!data)
+	if (data == NULL)
 		dbus_connection_remove_filter(connection, message_filter,
 						NULL);
 
@@ -480,7 +479,7 @@
 
 		/* Only auto remove if it is a bus name watch */
 		if (data->argument[0] == ':' &&
-				(!cb->conn_func || !cb->disc_func)) {
+				(cb->conn_func == NULL || cb->disc_func == NULL)) {
 			filter_data_remove_callback(data, cb);
 			continue;
 		}
@@ -517,7 +516,7 @@
 	/* Sender is always bus name */
 	data = filter_data_find(connection, NULL, sender, path, iface, member,
 					arg);
-	if (!data) {
+	if (data == NULL) {
 		error("Got %s.%s signal which has no listeners", iface, member);
 		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 	}
@@ -543,7 +542,7 @@
 	/* Remove filter if there no listener left for the connection */
 	data = filter_data_find(connection, NULL, NULL, NULL, NULL, NULL,
 					NULL);
-	if (!data)
+	if (data == NULL)
 		dbus_connection_remove_filter(connection, message_filter,
 						NULL);
 
@@ -658,18 +657,18 @@
 	struct filter_data *data;
 	struct filter_callback *cb;
 
-	if (!name)
+	if (name == NULL)
 		return 0;
 
 	data = filter_data_get(connection, service_filter, NULL, NULL,
 				DBUS_INTERFACE_DBUS, "NameOwnerChanged",
 				name);
-	if (!data)
+	if (data == NULL)
 		return 0;
 
 	cb = filter_data_add_callback(data, connect, disconnect, NULL, NULL,
 					user_data);
-	if (!cb)
+	if (cb == NULL)
 		return 0;
 
 	if (connect)
@@ -697,12 +696,12 @@
 
 	data = filter_data_get(connection, signal_filter, sender, path,
 				interface, member, NULL);
-	if (!data)
+	if (data == NULL)
 		return 0;
 
 	cb = filter_data_add_callback(data, NULL, NULL, function, destroy,
 					user_data);
-	if (!cb)
+	if (cb == NULL)
 		return 0;
 
 	if (data->name != NULL && data->name_watch == 0)