Use gdb::function_view in addrmap_foreach

Use gdb::function_view in addrmap_foreach

While working on the DWARF psymtab replacement, I needed
addrmap_foreach to accept a gdb::function_view.  This seemed like a
worthwhile change on its own, so I've written it separately for
submission.

Regression tested on x86-64 Fedora 32.

gdb/ChangeLog
2021-06-25  Tom Tromey  <tom@tromey.com>

	* dwarf2/index-write.c (struct addrmap_index_data): Add
	initializers.
	<operator()>: Declare.
	(addrmap_index_data::operator()): Rename from
	add_address_entry_worker.  Remove 'datap' parameter.
	(write_address_map): Update.
	* psymtab.c (struct dump_psymtab_addrmap_data): Remove
	(dump_psymtab_addrmap_1): Remove 'data' parameter, add other
	parameters.
	(dump_psymtab_addrmap): Update.
	* addrmap.c (struct addrmap_funcs) <foreach>: Remove 'data'
	parameter.
	(addrmap_foreach, addrmap_fixed_foreach): Likewise.
	(struct mutable_foreach_data): Remove.
	(addrmap_mutable_foreach_worker): Update.
	(addrmap_mutable_foreach): Remove 'data' parameter.
	* addrmap.h (addrmap_foreach_fn): Use gdb::function_view.
	(addrmap_foreach): Remove 'data' parameter.