* autoload.cc: Enable autoloading advapi32 functions.
* environ.cc (regopt): Use wide char arguments in reg_key functions.
* fhandler_console.cc (beep): Ditto. Use WCHAR throughout.
* registry.cc (reg_key): Rewrite reg_key class to use native NT registry
functions. Use WCHAR string parameters throughout. Use PCWSTR rather
than const WCHAR. Drop multibyte char functionality. Drop unused
methods.
(get_registry_hive_path): Use RtlQueryRegistryValues to fetch path from
registry.
(load_registry_hive): Drop useless check for user hive being available.
Load hive using NtLoadKey.
* registry.h: Accommodate above changes.
* sched.cc (sched_rr_get_interval): Use wide char arguments in reg_key
functions.
* shared.cc (init_installation_root): Ditto.
(shared_info::init_obcaseinsensitive): Use RtlQueryRegistryValues to
fetch obcaseinsensitive value.
(shared_info::heap_slop_size): Use wide char arguments in reg_key
functions.
(shared_info::heap_chunk_size): Ditto.
* syscalls.cc (gethostid): Ditto.
* winsup.h (__WIDE): Define.
(_WIDE): Define.
* libc/minires-os-if.c (get_registry_dns_items): Don't fetch values
from registry. Just extract them from given UNICODE_STRING parameter.
(get_registry_dns): Fetch all registry values at once using
RtlQueryRegistryValues.