Add constructor and destructor to demangle_parse_info

Add constructor and destructor to demangle_parse_info

This adds a constructor and destructor to demangle_parse_info, and
then changes all the users to use them.  This removes
make_cleanup_cp_demangled_name_parse_free and its single use.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* python/py-type.c (typy_legacy_template_argument): Update.
	* cp-support.h (struct demangle_parse_info) (demangle_parse_info,
	~demangle_parse_info): Declare new members.
	(cp_demangled_name_to_comp): Return unique_ptr.
	(cp_demangled_name_parse_free)
	(make_cleanup_cp_demangled_name_parse_free)
	(cp_new_demangle_parse_info): Remove.
	* cp-support.c (do_demangled_name_parse_free_cleanup)
	(make_cleanup_cp_demangled_name_parse_free): Remove.
	(inspect_type, cp_canonicalize_string_full)
	(cp_canonicalize_string): Update.
	(mangled_name_to_comp): Change return type.
	(cp_class_name_from_physname, method_name_from_physname)
	(cp_func_name, cp_remove_params): Update.
	* cp-name-parser.y (demangle_parse_info): New constructor, from
	cp_new_demangle_parse_info.
	(~demangle_parse_info): New destructor, from
	cp_demangled_name_parse_free.
	(cp_merge_demangle_parse_infos): Update.
	(cp_demangled_name_to_comp): Change return type.