add make_ext4fs to the libext4_utils

Move the bulk of make_ext4fs into libext4_utils, leaving a main() that
does only option parsing.  Add reset functionality so that
make_ext4fs() can be called multiple times within a process.

Change-Id: Ia09a2385eab32bf3ca9eb9257c4f9df2c85e55be
5 files changed