use proper error

modules/codec/flac.c

@@ -215,7 +215,7 @@ static int OpenDecoder( vlc_object_t *p_this )
           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
     {
         msg_Err( p_dec, "out of memory" );
-        return VLC_EGENERIC;
+        return VLC_ENOMEM;
     }
 
     /* Misc init */