o Minor bugfixes (fragile-hardening, sandbox):
    - When building with --enable-fragile-hardening, add or relax Linux
      seccomp rules to allow AddressSanitizer to execute normally if the
      process terminates with the sandbox active. This has the side
      effect of disabling the filtering of file- and directory-open
      requests on most systems and dilutes the effectiveness of the
      sandbox overall, as a wider range of system calls must be
      permitted. Fixes bug 11477; bugfix on 0.2.5.4-alpha.