RFR(trivial): 8223054: [TESTBUG] Put graalJarsCP before existing classpath in GraalUnitTestLauncher

[Pengfei Li (Arm Technology China)]

Thanks Igor.  Do I need another reviewer for this trivial change?

// Also cc graal-dev list

--
Thanks,
Pengfei

> 
> Looks good to me.
> 
> // moved to hotspot compiler list
> 
> — Igor
> 
> > On May 4, 2019, at 6:32 PM, Pengfei Li (Arm Technology China)
> <Pengfei.Li at arm.com> wrote:
> >
> > Hi,
> >
> > Please help review this trivial change on GraalUnitTestLauncher.
> >
> > Webrev: http://cr.openjdk.java.net/~pli/rfr/8223054/webrev.00/
> > JBS: https://bugs.openjdk.java.net/browse/JDK-8223054
> >
> > Current graal unit test in jtreg requires junit-4.12.jar as a dependency. In
> GraalUnitTestLauncher.java, we put the path of this file into graalJarsCP and
> concat it with existing classpath. But existing classpath may contain another
> version of junit with which the jtreg tool is built. (According to OpenJDK
> "Building jtreg" webpage[1], the recommended version of Junit to build jtreg
> is junit-4.10).
> >
> > In this patch, graalJarsCP is put before existing classpath returned by
> System.getProperty() when generating the new classpath string to avoid
> incompatibility issues. Jteg graal unit test cases passed after this change.
> >
> > [1] https://openjdk.java.net/jtreg/build.html
> >
> > --
> > Thanks,
> > Pengfei
> >