make a struct for dirents on linux, not a <c-object>

basis/io/directories/unix/linux/linux.factor

@@ -1,10 +1,11 @@
 ! Copyright (C) 2009 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: alien.c-types io.directories.unix kernel system unix ;
+USING: alien.c-types io.directories.unix kernel system unix
+classes.struct ;
 IN: io.directories.unix.linux
 
-M: unix find-next-file ( DIR* -- byte-array )
-    "dirent" <c-object>
+M: unix find-next-file ( DIR* -- dirent )
+    dirent <struct>
     f <void*>
     [ readdir64_r 0 = [ (io-error) ] unless ] 2keep
     *void* [ drop f ] unless ;