Update shadow to version 4.17.4 / rev 76 via SR 1254773
    
    https://build.opensuse.org/request/show/1254773
    by user jubalh + anag+factory
    - Update to 4.17.4:
      * Revert "lib/, src/: Use local time for human-readable dates"
      * lib/getdate.y: Ignore time-zone information and use UTC
      * src/chfn.c: Partially revert "lib/, src/: Use strsep(3) instead of its pattern"
      * src/chfn.c: Use stpsep() instead of its pattern
      * src/chfn.c: Add local variable to refer to the separated field
      * src/chfn.c: copy_field(): Rename local variable
      * lib/commonio.c: Rely on the POSIX.1-2008 behavior of realpath(3)
      * lib/fs/readlink/: readlinknul(): Use ssize_t to simplify
      * autogen.sh: Promote -Wsign-compare to an error
      * lib/sizeof.h: ssizeof(): Add signed variant of sizeof
      * src/lastlog.c: Use ssizeof() to avoid a -Wsign-compare diagnostic
      * tests/unit/test_xasprintf.c: Fix sign-mismatch diagnostic
      * configure.ac: stop checkin