Move int type methods out of dwarf2_per_cu_data

These methods rely on the current objfile to create types based on it.
Since dwarf2_per_cu_data is to become objfile-independent, these methods
need to mvoe.

int_type can be in dwarf2_per_objfile, as it only requires knowing about
the objfile.

addr_sized_int_type and addr_type also need to know about the DWARF
address type size, which is CU-specific.  The dwarf2_cu objects seems
like a good place for it, as it knows both about the current objfile and
the current CU.

gdb/ChangeLog:

	* dwarf2/read.h (struct dwarf2_per_cu_data) <addr_type,
	addr_sized_int_type>: Move to dwarf2_cu.
	<int_type>: Move to dwarf2_per_objfile.
	(struct dwarf2_per_objfile) <int_type>: Move here.
	* dwarf2/read.c (struct dwarf2_cu) <addr_type,
	addr_sized_int_type>: Move here.
	(read_func_scope): Update.
	(read_array_type): Update.
	(read_tag_string_type): Update.
	(attr_to_dynamic_prop): Update.
	(dwarf2_per_cu_data::int_type): Rename to...
	(dwarf2_per_objfile::int_type): ... this.
	(dwarf2_per_cu_data::addr_sized_int_type): Rename to...
	(dwarf2_cu::addr_sized_int_type): ... this.
	(read_subrange_type): Update.
	(dwarf2_per_cu_data::addr_type): Rename to...
	(dwarf2_cu::addr_type): ... this.
	(set_die_type): Update.

Change-Id: Ic4708ef99d43a8d99325ff91dee59b2eb706cb8f