- The test should also register a handler for VM_UNMAPPED, to make sure
  ucm_test_events(VM_UNMAPPED) would really return ERR_UNSUPPORTED after
  munmap() is overridden.
- Convert events to native events for mmap_test_installed_events(),
  otherwise they will be considered as not installed so testing their
  support will always return success, even when it should fail.

- Call sbrk(0) instead of nonzero offset, which can override application
  memory when running with valgrind