* libiberty/cp-demangle.c (struct demangling_def): New fields:

* libiberty/cp-demangle.c (struct demangling_def): New fields:
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.