tor-parallel-relay-conn/changes/bug31696

  o Major bugfixes (crash, Linux):
    - Tolerate systems (including some Linux installations) where madvise
      and/or MADV_DONTFORK are available at build-time, but not at run time.
      Previously, these systems would notice a failed syscall and abort.
      Fixes bug 31696; bugfix on 0.4.1.1-alpha.