RFR (S) JDK-8023735: runtime/XCheckJniJsig/XCheckJSig.java fails on MacOS X

[harold seigel]

Hi,

Please review this small change to fix bug 8023735.  The fix changes 
where the test looks for libjsig.dylib on Mac OS and also handles the 
case when libjsig is not there.  The change was tested on Mac OS and on 
Linux, with and without the existence of the libjsig file.

open webrev: http://cr.openjdk.java.net/~hseigel/bug_8023735/
<http://cr.openjdk.java.net/%7Ehseigel/bug_8023735/>
bug: https://bugs.openjdk.java.net/browse/JDK-8023735

Thanks! Harold