Avoid using KWSys auto_ptr by adopting it ourselves

Replace use of cmsys::auto_ptr with a CM_AUTO_PTR macro that maps to
our own implementation adopted from the KWSys auto_ptr implementation.
Later we may be able to map CM_AUTO_PTR to std::auto_ptr on compilers
that do not warn about it.

Automate the client site conversions:

    git grep -l auto_ptr -- Source/ | grep -v Source/kwsys/ | xargs sed -i \
      's|cmsys::auto_ptr|CM_AUTO_PTR|;s|cmsys/auto_ptr.hxx|cm_auto_ptr.hxx|'