Fix cppyy incompatibilities introduced with ROOT 6.22
- drop support for PyCintex (ROOT 5)
- stop using deprecated
cppyy.makeNamespace
- Workaround for ROOT-10769: cppyy warns about missing precompiled headers (see workaround in Gaudi: gaudi/Gaudi!1071 (fc07cf56))
Requires at least ROOT 6.20. @clemenci FYI
Edited by Marco Cattaneo