RFR(XS): 8154942 Remove ProcessTools.getVmInputArguments() from the hotspot test library, as it is not used by any of the hotspot tests

[George Triantafillou]

Please review this very small change that removes the unused method 
getVmInputArguments() from ProcessTools.

JBS: https://bugs.openjdk.java.net/browse/JDK-8154942
Webrev: 
http://cr.openjdk.java.net/~gtriantafill/bug-8154942/bug_8154942.patch/webrev/ 
<http://cr.openjdk.java.net/%7Egtriantafill/bug-8154942/bug_8154942.patch/webrev/>

Thanks,
George