cmake: use classic search for Eigen3

CMakeLists.txt

@@ -63,7 +63,7 @@ ENDIF(WIN32)
 # ----------------------------------------------------
 # --- DEPENDENCIES -----------------------------------
 # ----------------------------------------------------
-ADD_REQUIRED_DEPENDENCY("eigen3 >= 3.0.5")
+ADD_PROJECT_DEPENDENCY(Eigen3 REQUIRED PKG_CONFIG_REQUIRES "eigen3 >= 3.0.5")
 
 SET(BOOST_COMPONENTS python)
 SEARCH_FOR_BOOST()
@@ -183,7 +183,6 @@ ELSE()
 ENDIF()
 
 TARGET_LINK_BOOST_PYTHON(${PROJECT_NAME} PUBLIC)
-PKG_CONFIG_USE_DEPENDENCY(${PROJECT_NAME} eigen3)
 INSTALL(TARGETS ${PROJECT_NAME}
   EXPORT ${TARGETS_EXPORT_NAME}
   PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_FULL_INCLUDEDIR}