Rename address_space_int_to_name/address_space_name_to_int

These methods now take/return a type_instance_flags instead of a raw
integer, so rename them accordingly.

gdb/ChangeLog:

	* c-typeprint.c (c_type_print_modifier): Adjust to rename.
	* gdbtypes.c (address_space_name_to_int): Rename to ...
	(address_space_name_to_type_instance_flags): ... this.
	(address_space_int_to_name): Rename to ...
	(address_space_type_instance_flags_to_name): ... this.
	* gdbtypes.h (address_space_name_to_int): Rename to ...
	(address_space_name_to_type_instance_flags): ... this.
	(address_space_int_to_name): Rename to ...
	(address_space_type_instance_flags_to_name): ... this.
	* type-stack.c (type_stack::insert): Adjust to rename.
	* type-stack.h (type_stack::insert): Likewise.