Remove old-style package variable from the cmake config file

This leaves only the exported target in the file, which should be used.

LibtorrentRasterbarConfig.cmake.in

@@ -1,16 +1,9 @@
 # - Config file for the @PROJECT_NAME@ package
-# It defines the following variables
-#  @PROJECT_NAME@_INCLUDE_DIRS - include directories for @PROJECT_NAME@
-#  @PROJECT_NAME@_LIBRARIES    - libraries to link against
+# It defines the LibtorrentRasterbar::torrent-rasterbar target to link against
 
 @PACKAGE_INIT@
 
 include(CMakeFindDependencyMacro)
 @_find_dependency_calls@
 
 include("${CMAKE_CURRENT_LIST_DIR}/LibtorrentRasterbarTargets.cmake")
-
-get_target_property(@PROJECT_NAME@_INCLUDE_DIRS LibtorrentRasterbar::torrent-rasterbar INTERFACE_INCLUDE_DIRECTORIES)
-get_target_property(_lt_iface_link_libraries LibtorrentRasterbar::torrent-rasterbar INTERFACE_LINK_LIBRARIES)
-get_target_property(_lt_imported_location LibtorrentRasterbar::torrent-rasterbar IMPORTED_LOCATION)
-set(@PROJECT_NAME@_LIBRARIES "${_lt_imported_location};${_lt_iface_link_libraries}")