* external.cc (cygwin_internal): Make v1 mount table access invalid.

* external.cc (cygwin_internal): Make v1 mount table access invalid.
* path.cc (mount_info::init): Remove had_to_create_mount_areas initialization.
(mount_info::from_registry): Remove v1 table import.
(mount_info::read_v1_mounts): Eliminate.
(mount_info::import_v1_mounts): Ditto.
* shared_info.h (mount_info): Ditto for both of above.
* sys/mount.h (MOUNT_DEVFS): New enum.
(MOUNT_PROC): Ditto.