[InterNetNews/inn] 0c6d73: Use uintptr_t to convert a pointer to an integer

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: 0c6d73c9043b455e4be9287a2b7b8470d61ed284
      https://github.com/InterNetNews/inn/commit/0c6d73c9043b455e4be9287a2b7b8470d61ed284
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-11-02 (Thu, 02 Nov 2023)

  Changed paths:
    M configure.ac
    M lib/mmap.c
    M storage/cnfs/cnfs.c

  Log Message:
  -----------
  Use uintptr_t to convert a pointer to an integer

Issue seen on CheriBSD running on a Morello board
(capability-to-integer-cast error).

The relevant capability metadata for pointers is preserved in the
uintptr_t datatype.  This way, afterwards in the code, the other way
round of converting the computed integer value to a pointer works fine.