FindTDE: Conditional import of exported tdelibs targets.

This prevents multiple attempts to import exported tdelibs targets,
which would cause a collision if find_package( TDE ) is called
repeatedly for some reason.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit e51ecbd591)

modules/FindTDE.cmake

@@ -95,4 +95,6 @@ if( NOT TDE_FOUND )
 
 endif( NOT TDE_FOUND )
 
-include( "${TDE_CMAKE_DIR}/kdelibs.cmake" )
+if( NOT TARGET kdecore-shared )
+  include( "${TDE_CMAKE_DIR}/kdelibs.cmake" )
+endif()