Change dwarf2_cu::method_info to be a std::vector

Change dwarf2_cu::method_info to be a std::vector

This changes the type of dwarf2_cu::method_info and fixes up the uses.
In order to remove cleanups from process_full_comp_unit and
process_full_type_unit, psymtab_include_file_name also had to be
changed to avoid leaving dangling cleanups.

2018-01-17  Tom Tromey  <tom@tromey.com>

	* dwarf2read.c (delayed_method_info): Remove typedef.
	(dwarf2_cu::method_info): Now a std::vector.
	(add_to_method_list): Update.
	(free_delayed_list): Remove.
	(compute_delayed_physnames): Update.
	(process_full_comp_unit, process_full_type_unit): Clear the method
	list.  Remove cleanups.
	(psymtab_include_file_name): Add name_holder parameter.  Use
	unique_xmalloc_ptr.
	(dwarf_decode_lines): Update.