Changes for version 0.10
- Alter typedef of _Decimal128 for __MINGW64__ . (This became necessary with perl-5.28.0, but I've applied it universally whenever __MINGW64__ is defined.)
- "use 5.008;" in Makefile.PL.
- In XS code, replace (where practical) dynamic allocation of string buffer with static allocation.
- Prototype subroutines listed in 'use subs()'.
- Move POD out of Decimal128.pm and into (newly created) Decimal128.pod.
perl interface to C's _Decimal128 operations.