Throughout, revert prototypes and methods set_mtime_and_mode to

	Throughout, revert prototypes and methods set_mtime_and_mode to
	set_mtime and only care for the file timestamp.

	Throughout, accommodate additional mode_t parameter in call to
	io_stream::open.

	* IOStreamProvider.h (IOStreamProvider::open): Add mode_t parameter.
	* archive.cc (archive::extract_file): Reorder creation of in and tmp
	to get the file mode from the tar archive earlier.  Call io_stream::open
	with additional mode from tar archive.  Accommodate reversion to
	set_mtime.
	* filemanip.cc (nt_wfopen): Remove retry loop.  Instead initialize
	OBJECT_ATTRIBUTES with matching POSIX perms according to incoming
	perms to create correct ACL on file creation.  Remove subsequent call
	to nt_sec.SetPosixPerms.
	* io_stream.cc (io_stream::open): Take additional mode_t parameter
	and connect through to IOStreamProvider's open.
	* io_stream.h (io_stream::open): Add mode_t parameter.
	* io_stream_cygfile.cc (CygFileProvider::open): Ditto.
	(io_stream_cygfile::io_stream_cygfile): Ditto.  Call nt_wfopen with
	incoming mode_t parameter.  Make sure .exe and .dll files always
	have execute permissions set.
	(io_stream_cygfile::set_mtime): Remove retry loop and open file with
	just GENERIC_WRITE access.
	* io_stream_cygfile.h (io_stream_cygfile::io_stream_cygfile): Add mode_t
	parameter.
	* io_stream_file.cc (FileProvider::open): Ditto.
	(io_stream_file::io_stream_file): Ditto.  Call nt_wfopen with incoming
	mode_t parameter.
	* io_stream_file.h (io_stream_file::io_stream_file): Add mode_t
	parameter.
	* io_stream_memory.h (class io_stream_memory): Remove mode member.
	Just return 0 from get_mode.
	* mkdir.cc (mkdir_p): Remove retry loop.  Instead initialize
	OBJECT_ATTRIBUTES with matching POSIX perms according to incoming
	perms to create correct ACL on file creation.  Remove subsequent call
	to nt_sec.SetPosixPerms.
	* mklink2.cc (mkcygsymlink_nt): Remove retry loop.  Instead initialize
	SECURITY_ATTRIBUTES with matching POSIX perms to create correct ACL on
	file creation.
	* win32.cc (NTSecurity::GetPosixPerms): New function to generate
	POSIX ACL.  Default to current owner and current primary group for
	owner/group permissions.
	(NTSecurity::SetPosixPerms): Let GetPosixPerms create the DACL.
	(NTSecurity::setAdminGroup): Set groupSID to admins SID if successful.
	(NTSecurity::setDefaultSecurity): Store user SID in ownerSID member.
	Default groupSID to original primary group.
	* win32.h (struct acl_t): Define here.
	(class NTSecurity): Rename ownerSID and groupSID to cr_ownerSID and
	cr_groupSID.  Change throughout.  Add members ownerSID and groupSID.
	Declare new method GetPosixPerms.