Use %zu/%d to print size_t/ssize_t. Cast recno_t (a.k.a. u_int32_t)
to (unsigned long) to match %lu formats. Makes gcc happier and
quieter.

ok deraadt@

- check return from write(2) so we KNOW the data is on the disk
- remove unneeded variables
- add missing includes
ok deraadt

filesystem firmware loading written over the pacific 2 weeks ago, tested
by mickey