roota must contain all of libRoot.a and export all symbols.
Do not include pq2 in libROOT.a - and especially not its main().
Do not load the lib for a class if its dictionary is available.

Thsi prevents AutoLoad() of libraries that are statically linked.
Detect a static build, initialize TCling from process image instead of libCling.

libRoot.a now contains a symbol (usedToIdentifyStaticRoot() from
core/base/src/roota.cxx) that the regular build does not have. It is used to
initialize TCLing from the binary instead of dlopening libCling, just like in
the rootcling case.
Fix make static for ROOT 6.