RFR(S): 8192927: os::dir_is_empty is incorrect on Windows

[Calvin Cheung]

I've updated the change slightly:
- replaced the do-while loop with a while loop;
- free(search_path) should be os::free(search_path)

updated webrev: http://cr.openjdk.java.net/~ccheung/8192927/webrev.01/

thanks,
Calvin

On 12/19/17, 5:01 PM, Calvin Cheung wrote:
> bug: https://bugs.openjdk.java.net/browse/JDK-8192927
>
> This change is targeted for JDK 11.
> Please refer to the comment in the bug for a description of the 
> change. It also handles path longer than MAX_PATH.
>
> webrev: http://cr.openjdk.java.net/~ccheung/8192927/webrev.00/
>
> Testing:
>     hs-tier1, hs-tier2 on linux-x64, windows-x64, macosx
>     appcds tests on the above platforms + sparcv9.
>
> thanks,
> Calvin