mke2fs: don't set root dir UID/GID automatically

mke2fs: don't set root dir UID/GID automatically

Don't change the root directory's UID/GID automatically just because
mke2fs was run as a non-root user.  This can be confusing for users,
and is not flexible for non-root installation tools that need to
create a filesystem with different ownership from the current user.

Add the "-E root_owner[=uid:gid]" option to mke2fs so that the user
and group can be explicitly specified for the root directory.  If
the "=uid:gid" argument is not specified, the current UID and GID
are extracted from the running process, as was done in the past.

Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>