installation_proxy: Silence compiler warnings about thread_t pointer assignments

src/installation_proxy.c

diff --git a/src/installation_proxy.c b/src/installation_proxy.c
index c49014d..b1dfeb4 100644
--- a/src/installation_proxy.c
+++ b/src/installation_proxy.c
@@ -105,7 +105,7 @@
 	instproxy_client_t client_loc = (instproxy_client_t) malloc(sizeof(struct instproxy_client_private));
 	client_loc->parent = plistclient;
 	mutex_init(&client_loc->mutex);
-	client_loc->status_updater = NULL;
+	client_loc->status_updater = (thread_t)NULL;
 
 	*client = client_loc;
 	return INSTPROXY_E_SUCCESS;
@@ -354,7 +354,7 @@
 	if (data->operation) {
 	    free(data->operation);
 	}
-	data->client->status_updater = NULL;
+	data->client->status_updater = (thread_t)NULL;
 	instproxy_unlock(data->client);
 	free(data);
 

src/notification_proxy.c

diff --git a/src/notification_proxy.c b/src/notification_proxy.c
index 952e5f2..291c257 100644
--- a/src/notification_proxy.c
+++ b/src/notification_proxy.c
@@ -110,7 +110,7 @@
 	client_loc->parent = plistclient;
 
 	mutex_init(&client_loc->mutex);
-	client_loc->notifier = NULL;
+	client_loc->notifier = (thread_t)NULL;
 
 	*client = client_loc;
 	return NP_E_SUCCESS;
@@ -395,7 +395,7 @@
 		property_list_service_client_t parent = client->parent;
 		client->parent = NULL;
 		thread_join(client->notifier);
-		client->notifier = NULL;
+		client->notifier = (thread_t)NULL;
 		client->parent = parent;
 	}