Remove --reduce-memory-overheads and --hash-size arguments.

Remove --reduce-memory-overheads and --hash-size arguments.

	* NEWS: Mention --reduce-memory-overheads and --hash-size arguments
	options.
	* as.c: Remove the options from help.
	* doc/as.texi: Remove options.
	* doc/internals.texi: Remove hash from documentation.
	* hash.c (struct hash_entry): Remove.
	(struct hash_control): Likewise.
	(set_gas_hash_table_size): Likewise.
	(hash_new_sized): Likewise.
	(hash_new): Likewise.
	(hash_die): Likewise.
	(hash_lookup): Likewise.
	(hash_insert): Likewise.
	(hash_jam): Likewise.
	(hash_replace): Likewise.
	(hash_find): Likewise.
	(hash_find_n): Likewise.
	(hash_delete): Likewise.
	(hash_traverse): Likewise.
	(hash_print_statistics): Likewise.
	(TABLES): Likewise.
	(STATBUFSIZE): Likewise.
	(main): Likewise.
	(what): Likewise.
	(destroy): Likewise.
	(applicatee): Likewise.
	(whattable): Likewise.
	* hash.h (struct hash_control): Likewise.
	(set_gas_hash_table_size): Likewise.
	(hash_new): Likewise.
	(hash_new_sized): Likewise.
	(hash_die): Likewise.
	(hash_insert): Likewise.
	(hash_jam): Likewise.
	(hash_replace): Likewise.
	(hash_find): Likewise.
	(hash_find_n): Likewise.
	(hash_delete): Likewise.
	(hash_traverse): Likewise.
	(hash_print_statistics): Likewise.