distrib/ext4_utils: new third-party library sources.

This patch adds the sources for the ext4_utils library that
will be used to create empty ext4 partition images on demand.

This is necessary to get rid of the YAFFS2 cache partition images
that are no longer supported by the next version of the Android
kernel (3.10).

Change-Id: Ia12bbb4d9cb31600c25ea6f66446ed98a7e85b1f
41 files changed