use DESTDIR properly

cmake/Modules/ClhepBuildLibrary.cmake

@@ -91,9 +91,9 @@ macro(clhep_build_libclhep )
   else()
       # create the symbolic links
       file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/clhep_static_symlink 
-        	 "execute_process(COMMAND \"${CMAKE_COMMAND}\" -E create_symlink ${CMAKE_STATIC_LIBRARY_PREFIX}CLHEP-${VERSION}${CMAKE_STATIC_LIBRARY_SUFFIX} ${CMAKE_STATIC_LIBRARY_PREFIX}CLHEP${CMAKE_STATIC_LIBRARY_SUFFIX} WORKING_DIRECTORY \"$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}\" )" )
+        	 "execute_process(COMMAND \"${CMAKE_COMMAND}\" -E create_symlink ${CMAKE_STATIC_LIBRARY_PREFIX}CLHEP-${VERSION}${CMAKE_STATIC_LIBRARY_SUFFIX} ${CMAKE_STATIC_LIBRARY_PREFIX}CLHEP${CMAKE_STATIC_LIBRARY_SUFFIX} WORKING_DIRECTORY \"\$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}\" )" )
       file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/clhep_shared_symlink 
-        	 "execute_process(COMMAND \"${CMAKE_COMMAND}\" -E create_symlink ${CMAKE_SHARED_LIBRARY_PREFIX}CLHEP-${VERSION}${CMAKE_SHARED_LIBRARY_SUFFIX} ${CMAKE_SHARED_LIBRARY_PREFIX}CLHEP${CMAKE_SHARED_LIBRARY_SUFFIX} WORKING_DIRECTORY \"$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}\" )" )
+        	 "execute_process(COMMAND \"${CMAKE_COMMAND}\" -E create_symlink ${CMAKE_SHARED_LIBRARY_PREFIX}CLHEP-${VERSION}${CMAKE_SHARED_LIBRARY_SUFFIX} ${CMAKE_SHARED_LIBRARY_PREFIX}CLHEP${CMAKE_SHARED_LIBRARY_SUFFIX} WORKING_DIRECTORY \"\$ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}\" )" )
   endif()
 
   INSTALL(SCRIPT ${CMAKE_CURRENT_BINARY_DIR}/clhep_static_symlink )