We can be sure that at least cmake 2.6.3 is used when building cmcurl.
This means we always get in the first branch of the if().
I think it is not a good idea to pull a cmake module from the cmake
which is being built in, since this may use features which are not
supported in the cmake which is used to build cmake (e.g. CMAKE_CURRENT_LIST_DIR
which does not exist in cmake 2.6.3 which is the minimum for cmcurl).
A bit further below there is anyway code to handle the case that cmake is
older than 2.8.0, so it should be ok.
Alex