MFC 271635,271722:

• Only the manpage updates from 271635 are merged to give additional heads up for the stricter checks in 11, but the kernel in 10 remains permissive.
  • Fail with EINVAL if an invalid protection mask is passed to mmap().
  • Fail with EINVAL if an unknown flag is passed to mmap().
  • Fail with EINVAL if both MAP_PRIVATE and MAP_SHARED are passed to mmap().
  • Require one of either MAP_PRIVATE or MAP_SHARED for non-anonymous mappings.
• Remove mention of MAP_INHERIT. It hasn't been implemented for thirteen years.
• Remove mention of unimplemented MAP_SWAP. There are no future plans to implement it.