RFR 6722928: Support SSPI as a native GSS-API provider

[Weijun Wang]

I uploaded an updated webrev in place. The only changes are:

1. s/SSPI_TRACE/SSPI_BRIDGE_TRACE/ in sspi.cpp
2. Several copyright year updates.
3. Remove one unused import.

Thanks,
Max

> On May 30, 2019, at 11:18 AM, Weijun Wang <weijun.wang at oracle.com> wrote:
> 
> Here is the latest webrev
> 
>   http://cr.openjdk.java.net/~weijun/6722928/webrev.07/