BUILD: Support cmake < 3.20

Author: JanWielemaker

cmake/InstallSource.cmake

@@ -139,7 +139,11 @@ function(install_in_home name)
 		"Cannot link from build home: ${file} does not exist")
       endif()
       add_symlink_command(${file} ${buildhome}/${base})
-      cmake_path(SET dep NORMALIZE ${buildhome}/${base})
+      if (CMAKE_VERSION VERSION_GREATER_EQUAL "3.20")
+	cmake_path(SET dep NORMALIZE ${buildhome}/${base})
+      else()
+	set(dep ${buildhome}/${base})
+      endif()
       set(deps ${deps} ${dep})
     endforeach()