Remove `atlas_depends_on_subdirs` and tidy link dependencies.

In the past there was a (very fragile) feature in atlas_add_root_dictionary(...)
that allowed it to scan the include definitions in a LinkDef.h file, and construct
the rootcint command based on that.

This feature has now been removed, as it was one of the most fragile parts
of our code. Now all users of atlas_add_root_dictionary(...) must declare explicitly
in CMake which headers they want to generate dictionaries for.

James Catmore authored 7 years ago and Atlas Nightlybuild committed 7 years ago

21.2 add analysis top and project

See merge request !2226

Former-commit-id: a0735f8910b2316b75d3535bd5b9b2a6110723b7