XS.xs: rely more on __builtin_expect
XS.xs: rely more on __builtin_expect

With the improvement in infrastructure we can rely with greater outcome on
__builtin_expect which leads to up to 5% better performance on some inner
loops.

This affects even more older Perls or otherwise broken configurations
because of trying to run compliled tests leading to false negatives as
probe result.

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

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