server: Avoid invalid memory access if creation of namespace fails in create_directory (Coverity).

server/directory.c

@@ -192,7 +192,7 @@ static struct directory *create_directory( struct directory *root, const struct
         if (!(dir->entries = create_namespace( hash_size )))
         {
             release_object( dir );
-            dir = NULL;
+            return NULL;
         }
         if (sd) default_set_sd( &dir->obj, sd, OWNER_SECURITY_INFORMATION | GROUP_SECURITY_INFORMATION |
                                 DACL_SECURITY_INFORMATION | SACL_SECURITY_INFORMATION );