[pdal] Pdal-2.1.0 and libproj

[Rich Shepard]

I'm running Slackware-14.2/x86_64 and both proj-7.0.1 and pdal-2.1.0 are
installed.

When building GRASS 7.9.dev from the git repo the attempt fails because it's
looking for 'v.in.pdal: error while loading shared libraries: libproj.so.15:
cannot open shared object file: No such file or directory.'

That's because proj-7.0.1 installs libproj.so.19.

GRASS supports proj7 and I need to learn how to allow pdal to use the newer
libproj.

I need your advice, suggestions, and recommendations.

Regards,

Rich