Build in the usual way:

perl Makefile.PL
make test
make install

For that to work, you'll need a compiler that provides support for the _Decimal128 type.

If your compiler provides the strtod128 function and you want to make use of it, either
provide the Makefile.PL with the command line argument STRTOD128=1, or edit the Makefile.PL
to set $strtod128 to 1.

Cheers,
Rob