$NetBSD$

Use cmake variable for libdl.
https://github.com/doctest/doctest/pull/848

--- examples/executable_dll_and_plugin/CMakeLists.txt.orig	2023-03-15 12:35:44.000000000 +0000
+++ examples/executable_dll_and_plugin/CMakeLists.txt
@@ -12,7 +12,7 @@ target_link_libraries(executable_dll_and
 target_link_libraries(executable_dll_and_plugin implementation)
 
 if(NOT WIN32)
-    target_link_libraries(executable_dll_and_plugin dl)
+    target_link_libraries(executable_dll_and_plugin ${CMAKE_DL_LIBS})
 endif()
 
 # have the executable depend on the plugin so it gets built as well when building/starting only the executable