copy: fix --reflink=auto to fallback in more cases

copy: fix --reflink=auto to fallback in more cases

On restricted systems like android or some containers,
FICLONE could return EPERM, EACCES, or ENOTTY,
which would have induced the command to fail to copy
rather than falling back to a more standard copy.

* src/copy.c (is_terminal_failure): A new function refactored
from handle_clone_fail().
(is_CLONENOTSUP): Merge in the handling of EACCES, ENOTTY, EPERM
as they also pertain to determination of whether cloning is supported
if we ever use this function in that context.
(handle_clone_fail): Use is_terminal_failure() in all cases,
so that we assume a terminal failure in less errno cases.
* NEWS: Mention the bug fix.
Addresses https://bugs.gnu.org/62404