The output directory for hotspot's JTReg tests, when run via the top-level Makefile targets such as test-hotspot-jtreg, is <top-level>/build/<conf>/hotspot/linux-x64/testoutput (on an x86-64 machine running Linux). There is no need to place the testoutput directory in a directory which name is based on OS and arch, that is already decided by the current configuration. Therefore, we can instead place the testoutput in <top-level>/build/<conf>/testouput/<jtreg-group>, which jdk/test/Makefile also uses.