Fix regression in #pragma cling add_library_path().
Fix regression in #pragma cling add_library_path().

This regression was introduced by root-project/root@561e905b where we stopped
iterating, on every lookup, over the -L paths passed at start up.

This patch adds the path to the search paths of the DynamicLibraryManager
rather than to the invocation options.

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root