fix squeeze's cmake 2.8.2 undefined CMAKE_CURRENT_LIST_DIR

[jschueller]

it's ok too, wouldn't it be:

if(NOT DEFINED CMAKE_CURRENT_LIST_DIR )

?

I've checked the documentation for the first version defining CMAKE_CURRENT_LIST_DIR.

[jschueller]

ok, modified

[dbarbier]

If I understand http://public.kitware.com/Bug/view.php?id=11675 some CMake version did define an empty CMAKE_CURRENT_LIST_DIR variable, this is why it is better to drop DEFINED.

[jschueller]

ok, just tested it on squeeze