e4defrag: adjust total count when files change during the run

e4defrag: adjust total count when files change during the run

If files are created while e4defrag is running, it's quite possible
for succeed_cnt to be larger than total_count, in which case the
number of failures (calculated via total_count - succeed_cnt) will
overflow and become a very large unsigned number.

The way we calculate statistics is a bit silly, since when recurse
into directories is counted, it's counted as a "failure".  But we'll
ignore this from now, and avoid the unsigned overflow.

Address-Debian-Bug: #888899

Signed-off-by: Theodore Ts'o <tytso@mit.edu>