Revert "bindings: perl: Do not link against libperl."

[rakuco]

This reverts commit 5077b75.

The original change breaks linking with -Wl,--no-undefined, which is the
default on distros such as Fedora and Debian, and it also makes some
sanity tests on FreeBSD to fail since the code uses Perl symbols but
does not link against libperl.so. There does not seem to be a big
benefit in building the binding with a Perl version other than the
installed on, especially since most distros simply rebuild everything
when switching Perl versions.

[DimStar77]

There are at least some distros that prefer not to rebuild for a perl update if not needed (especially rolling releases)

The perl library is always loaded in a perl context, so the symbols are there.

I would accept a patch for -DFORCE_PERL_LINKING:BOOL=ON to enable this - then it's an option for the respective distro which way they want it.

Does that sound reasonable?

[rakuco]

How about making this dependent on PERL_VENDORINSTALL instead? I can see that ArchLinux installs its Perl .so files into the vendor_perl directory, and in this case I guess it makes more sense to make it independent of a specific libperl.so, but if one's installing into a versioned Perl directory it means it will be rebuilt on each Perl update anyway.

Another compromise solution could be making the default value of the FORCE_PERL_LINKING option depend on PERL_VENDORINSTALL.

[DimStar77]

I like the 2nd approach, have PERL_LINK_LIBPERL (probably a better name, as it starts with PERL_) default based on PERL_VENDORINSTALL...

That should make it work properly for Arch and for Fedora - and the ones that still want it different to the defined default can override it.

[rakuco]

Alright, done in #14.