* postinstall: New script.

	* postinstall: New script.
	* Makefile.in (sysconfdir): Define.
	(install): Create $(sysconfdir)/postinstall dir.  Install postinstall
	script into it.

	* path.cc: Add temorary comments to note later function removal.
	(conv_fstab_spaces): New inline function to handle \040 to space
	conversion.
	(struct opt): Add "system" and "user" mount options.
	(mount_info::from_fstab_line): Only allow # to start a comment at
	the beginning of the line.  Call conv_fstab_spaces on native_path and
	posix_path fields.  Don't enforce system mounts in /etc/fstab.
	Drop last argument in call to add_item.
	(mount_info::from_fstab): Create a default cygdrive entry.  Load
	user mount points from fstab.<username> instead of fstab.<sid>.
	(mount_info::read_mounts): Drop last argument in call to add_item.
	(mount_info::add_reg_mount): Remove.
	(mount_info::del_reg_mount): Remove.
	(mount_info::write_cygdrive_info): Rename from
	mount_info::write_cygdrive_info_to_registry.  Don't write to registry.
	Disallow to overwrite a system cygdrive prefix.
	(mount_info::remove_cygdrive_info_from_registry): Remove.
	(mount_info::get_cygdrive_info): Just fetch current cygdrive prefix and
	flags.
	(mount_info::add_item): Drop last argument.  Don't write to registry.
	Disallow to overwrite a system mount point.
	(mount_info::del_item): Drop last argument.  Don't write to registry.
	Disallow to remove a system mount point.
	(mount): Enforce user mount.
	(cygwin_umount): Ditto.
	* shared_info.h (mount_info::add_item): Drop last argument.
	(mount_info::del_item): Ditto.
	(mount_info::add_reg_mount): Remove.
	(mount_info::del_reg_mount): Remove.
	(mount_info::write_cygdrive_info): Rename from
	mount_info::write_cygdrive_info_to_registry.
	(mount_info::remove_cygdrive_info_from_registry): Remove.