RFR (S) 8183229: Implement WindowsSemaphore::trywait

[Kim Barrett]

> On Jun 29, 2017, at 8:50 AM, Mikael Gerdin <mikael.gerdin at oracle.com> wrote:
> 
> Hi all,
> 
> To help with some upcoming patches I'd like to add the trywait operation to the platform-independent Semaphore class. It's currently lacking a Windows-implementation.
> 
> Testing: JPRT testing on Windows platforms
> Webrev: http://cr.openjdk.java.net/~mgerdin/8183229/webrev.0/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8183229
> 
> Thanks
> /Mikael

Code looks good, but needs a test for the new function in hotspot/test/native/runtime/test_semaphore.cpp.