is_constructor and is_destructor.
(demangling_new): Initialize them.
(demangle_ctor_dtor_name): Set them, if we detect a constructor
or destructor.
(demangle_v3_with_details, is_gnu_v3_mangled_ctor,
is_gnu_v3_mangled_dtor): New functions.
* include/demangle.h (enum gnu_v3_constructor_kinds,
is_gnu_v3_mangled_ctor, enum gnu_v3_destructor_kinds,
is_gnu_v3_mangled_dtor): New declarations.
* cplus-dem.c: Likewise.
(current_demangling_style): Now auto_demangling.
(cplus_demangle): Try v3 demangling if AUTO_DEMANGLING.
(main): Use standard symbol chars for auto_demangling.