ASAN allocates a huge amount of shadow memory when it runs. This make it impossible to dump core if an ASAN enabled test fails.  To ameliorate this issue and get more useful information in for these failures we should:

1. Run ASAN tests with the unmap_shadow_on_exit=1 set in the ASAN_OPTIONS.  If ASAN detects an error, this should cause it to release its shadow memory before attempting to dump core.
2. Update the hang analyzer so that it doesn't try to generate core files after attaching gdb to a ASAN binary.  (Or, better, figure out how to unmap the shadow memory via gdb so it can dump core.)