Fix more wrong sizeof() usages, part 3/x

Fix more wrong sizeof() usages, part 3/x

Some comments:

* The gzip fix speeds up uncompression of compress(1)'d files with gzip.
  A test here took 9s with the fix when it previously took 15s.

* Our OpenSSH is without J-PAKE support, hence the OpenSSH fix is only
  cosmetical.

Found-with: Coccinelle (http://coccinelle.lip6.fr/)