Revert "Add appropriate flag. file_system::file_string is deprecated since boost 1.46."

This reverts commit 8fc08b88.

src/CMakeLists.txt

@@ -46,17 +46,8 @@ INSTALL(TARGETS ${LIBRARY_NAME}
   DESTINATION lib)
 
 SET(EXECUTABLE_NAME dg-python)
-
-IF (${Boost_VERSION} VERSION_GREATER "1.45")
-   MESSAGE(STATUS "Adding deprecated flag to boost")
-   ADD_DEFINITIONS(-DBOOST_FILESYSTEM_DEPRECATED)
-ENDIF()
-
-
-
 ADD_EXECUTABLE(${EXECUTABLE_NAME} dg-python.cc)
 TARGET_LINK_LIBRARIES(${EXECUTABLE_NAME}
-  ${Boost_LIBRARIES}
   ${LIBRARY_NAME}
   )
 INSTALL(TARGETS dg-python DESTINATION bin)