Link against ${CMAKE_DL_LIBS} instead of libdl.
Link against ${CMAKE_DL_LIBS} instead of libdl.

-dl only exists on Linux, so linking fails on other OSes like FreeBSD.
Use the portable CMAKE_DL_LIBS variable instead.

lucadelu/PDAL,lucadelu/PDAL,lucadelu/PDAL,lucadelu/PDAL