Fix deprecated CMake TARGET/LOCATION property

CMake 3.9-rc2 says that CMP0026 = OLD will be removed "in the future"...

EXTERNAL/csparse/CMakeLists.txt

@@ -74,10 +74,7 @@ FILE(GLOB headers "${CMAKE_CURRENT_SOURCE_DIR}/*.h" "${CMAKE_CURRENT_SOURCE_DIR}
 INSTALL(FILES ${headers} DESTINATION ${CMAKE_INSTALL_PREFIX}/include/EXTERNAL/csparse)
 
 # Set up the variables
-if(POLICY CMP0026)
-  cmake_policy(SET CMP0026 OLD)
-endif()
-GET_TARGET_PROPERTY(CSPARSE_LIBRARY csparse LOCATION)
+SET(CSPARSE_LIBRARY "$<TARGET_FILE:csparse>")
 SET(CSPARSE_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE PATH "Include directory for CSparse" FORCE)
 SET(CSPARSE_LIBRARY     ${CSPARSE_LIBRARY} CACHE FILEPATH "CSparse library" FORCE)
 #SET(CSPARSE_FOUND TRUE PARENT_SCOPE)