currently, jtreg uses the latest -k flag, so it's hard for execution scripts, including jdk makefiles, to use several keywords for filtering.

jdk10 makefiles use -k flags for hotspot tests:
 -k:!ignore to filter out excluded tests
 -k:!headful to filter out tests which require JDK under test to be headful
but only the last (-k:!ignore) is used, as a result we are getting failures on headless configurations.