On qemuarm64 systems, about half of the valgrind tests fail and
often result in defunct processes, eg:
root 819 818 25 00:12 pts/0 00:01:52 /usr/bin/valgrind --command-line-only=yes --memcheck:leak-check=no --tool=memcheck -q --track-origins=
root 861 420 0 00:13 pts/0 00:00:00 [sh] <defunct>
Eventually these processes use so much memory that the
out of memory killer runs.
Hide the tests that fail as a horrid work-around until the
root cause has been resolved since this at least allows the
ptest run to complete. This work-around is done in the run-ptest
script using a sorted list of tests so that they can be easily
restored one by one without a rebuild during testing.
