lima/fixClangWarnings - fixes several compilation warnings when building Geant4 with VecGeom shapes

During last week's code sprint, Gabriele reported a lot of warnings coming from VecGeom headers, when building Geant4 libraries with VecGeom shapes. Those are fixed in one of the commits.

The other commit fixes a few compilation warnings, when building VecGeom in release mode. The warnings were due to variables defined, and used only within assert()s, which were sometimes disabled in Release mode. The fix was to ensure the assert()s are not disabled for those tests, by #undef'ing NDEBUG before loading other header files.