PR symtab/12302

	PR symtab/12302
	* dwarf2read.c (struct psymtab_cu_index_map): New struct.
	(hash_psymtab_cu_index, eq_psymtab_cu_index): New functions.
	(struct addrmap_index_data): New struct.
	(add_address_entry): Remove arg `pst', new args `start', `end'.
	(add_address_entry_worker, write_address_map): New functions.
	(write_psymtabs_to_index): Address table generation moved to
	write_address_map.  Build a table mapping psymtab to CU index
	to pass to it.