openzfs: Fix GCC 14 warnings
This is a direct cherry-pick to stable/13 of OpenZFS commit
4840f023afae7c4932c903cf3a436c02c6704e20:
GCC: Fixes for gcc 14 on Fedora 40 - Workaround dangling pointer in uu_list.c (#16124) - Fix calloc() transposed arguments in zpool_vdev_os.c - Make some temp variables unsigned to prevent triggering a '-Werror=alloc-size-larger-than' error. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #16124 Closes #16125