add(sys-apps/util-linux): Add patched util-linux to support PARTTYPE

This adds support for PARTTYPE in libblkid so cgpt use it instead of
implementing its own partition probing/searching logic.

Patches submitted upstream, no response yet: http://thread.gmane.org/gmane.linux.utilities.util-linux-ng/8392

Required to support cgpt resize's default behavior of searching for the `coreos-resize` partition type. https://github.com/coreos/vboot_reference/pull/9