Since commit deabd4a, psl2c has been replaced by psl-make-dafsa.
The builtin PSL data is always generated the same way, and the value of the builtin
configure option does not matter anymore.
The built-in data is now embedded by default (instead of the previous "auto"), unless
explicitly disabled by --disable-builtin/-Dbuiltin=false.
When not using an run-time runtime IDNA library (--disable-runtime/-Druntime=no), libpsl can
now include the built-in data without any build-time dependency.