o) make use of the new normalized types
 o) implementation of const& converters
 o) bunch of old workarounds removed
 o) new workaround added for _Tp_alloc_type
 o) removed some obsolete header #include's and decls


git-svn-id: https://root.cern.ch/svn/root/trunk@48777 27541ba8-7e3a-0410-8455-c3a389f83636
When looking at the whether the target is in std, let's look at the final target (rather than just one hop). Desugar Elaborated type (inside the type chain).


git-svn-id: https://root.cern.ch/svn/root/trunk@48778 27541ba8-7e3a-0410-8455-c3a389f83636