Perls with longdouble and quadmath

[DrHyde]

Similar to #420 it would be nice to be able to request a perl built with -Duselongdouble or -Dusequadmath.

NB that quadmath is a gcc-ism so probably isn't available on Windows.

[zmughal]

This would be useful for me as well for testing PDL's ldouble() type support.

[DrHyde]

FYI for now my work-around is to use perlbrew to roll my own: https://github.com/DrHyde/perl-modules-Data-CompactReadonly/blob/master/.github/workflows/weird-perls.yml

[sanko]

@DrHyde, you could cache the built perls with Github's own actions/cache. It's what I did for https://github.com/sanko/Affix.pm/blob/main/.github/workflows/ci.yaml.

The majority of that workflow is there to work around perlbrew being incompatible with Windows but it runs over 100 different platform and build flag combinations... caching has been a real time saver.