Split openFileForRead into Windows and Unix versions

[Rafael Espíndola]

On 17 July 2013 07:52, Reid Kleckner <rnk at google.com> wrote:
> LGTM
>
> We could pass FILE_SHARE_DELETE/WRITE to pretend to be more POSIX
> filesystem-y, but that's really futile and all the other native tools block
> file writes and deletes anyway.

I don't have a preference (first time ever using this API).  I
committed with FILE_SHARE_READ. Let me know if you want me to add
FILE_SHARE_DELETE and FILE_SHARE_WRITE.

Cheers,
Rafael