Reduce SelectSaver memory footprint

Reduce SelectSaver memory footprint

This is saving about 500k when using SelectSaver
as most of the time Carp is not required.

before> perl -I. -e 'require q{lib/SelectSaver.pm}; print qx{grep VmRSS /proc/$$/status}'
VmRSS:      2920 kB

after> perl -I. -e 'require q{lib/SelectSaver.pm}; print qx{grep VmRSS /proc/$$/status}'
VmRSS:      2352 kB

Committer:  Increment SelectSaver $VERSION.  Add perldelta entry for SelectSaver.

For: RT # 129235