[8u] 8205916: [test] Fix jdk/tools/launcher/RunpathTest to handle both, RPATH and RUNPATH

[Liu, Xin]

Hi, Reviewers,

Bug: https://bugs.openjdk.java.net/browse/JDK-8205916
Webrev: https://cr.openjdk.java.net/~xliu/8205916/webrev.00/

Some systems, including AmazonLinux , choose to generate RUNPATH over RPATH.
We have to apply this patch to pass jtreg tests.  The backport patch applies clearly.

Thanks,
--lx