Implemented NtSignalAndWaitForSingleObject.

diff --git a/server/snapshot.c b/server/snapshot.c
index 975728a..61265ba 100644
--- a/server/snapshot.c
+++ b/server/snapshot.c
@@ -61,6 +61,7 @@
     NULL,                         /* remove_queue */
     NULL,                         /* signaled */
     NULL,                         /* satisfied */
+    no_signal,                    /* signal */
     no_get_fd,                    /* get_fd */
     snapshot_destroy              /* destroy */
 };