XS.xs: first shot in direction of refcounting bug
XS.xs: first shot in direction of refcounting bug

In RT#123868 Zefram reported an issue with the reduce_* functions regarding
to proper reference counting.

This is a first attempt in direction of fixing this by adopting 16ada235 from
perl core and asking for code review afterwards ...

Signed-off-by: Jens Rehsack <69d49c504a9219a55b8be0f905e8fe3c32ffb57f@netbsd.org>

perl5-utils/List-MoreUtils-XS,perl5-utils/List-MoreUtils-XS