openjdk8: bump jdk8_hotspot.
openjdk8: bump jdk8_hotspot.

* now use a stable jtreg tarball
* build with one job, avoids having multiple JVM running.

nielx/haikuports,moochris/haikuports,Begasus/haikuports,nielx/haikuports,haikuports/haikuports,moochris/haikuports,Begasus/haikuports,Begasus/haikuports,haikuports/haikuports,Begasus/haikuports,Begasus/haikuports,moochris/haikuports,haikuports/haikuports,nielx/haikuports,haikuports/haikuports,haikuports/haikuports