The test should reuse the prebuilt modules in the module cache. However,
due to a mismatch between the module-related flags exported by FindROOT.
There is a mismatch between the -D passed by cmake.

This patch make sure that the build arguments match more closely the build
setup of ROOT. Thus we can reuse the already built module files.

[RDF,Tutorial] Add tutorial processing NanoAOD-like file producing dimuon spectrum from Run2011A CMS OpenData

Use pointer to const object rather than const pointer to non-const
object.

Sometimes the serialised methods will fail to load due to missing files.
This adds more output and checks to verify that required files exist to
better pinpoint the problem.

Removes unused spectator expression.
Removes weird weighting and replaces it with an informative comment.