Use rewinddir to count number of files

[cxong]

Use rewinddir to count number of files

[lautis0503]

What about malloc() a small block of memory (maybe size * 12, I guess), and realloc() another block when needed? Will need only one-pass. Might be slower, but safer about race condition.
There could be a balance between safety and efficiency.

[cxong]

I tried a doubling realloc implementation before but counting in two passes was faster on a folder with 10000 items. Anyway rewinddir should be both fast and safe. See #6