RFR (10) (S) 8175817: Clean up Solaris signal code: SIGUSR2, SIGasync, SIGJVM1/2

[David Holmes]

Can I get a Review please.

Thanks,
David

On 16/03/2017 11:00 PM, David Holmes wrote:
> Bug: https://bugs.openjdk.java.net/browse/JDK-8175817
>
> webrev: http://cr.openjdk.java.net/~dholmes/8175817/webrev/
>
> On Solaris SIGasync represents what we call the "SR signal" on other
> platforms (the event-based suspend/resume signal), and it is hardwired
> to SIGJVM2 (a dedicated JVM signal on Solaris 10+).
>
> As this signal is hard-wired and has not been user-definable at runtime
> for a very long time, we can do away with the SIGasync field and its
> setter and getter, and simply define ASYNC_SIGNAL as SIGJVM2 (not
> SIGUSR2 as the code currently suggests!). Once this is a build time
> constant it simplifies some other code.
>
> We can also stop trying to account for SIGJVM1/2 not existing as they
> must exist on the supported Solaris platforms.
>
> We can also stop trying to deal with an older libjsig (the logic for
> which has a bug anyway: used <= instead of < in the version check).
>
> Overall just a bit of simplification and cleanup. No functional changes.
>
> Testing: JPRT
>
> Thanks,
> David
>