Add test case for CVE-2013-1416

ticket: 7635 (new)
Fix check for KDB: prefix in kinit

The string "KDB:" has four characters, not three; check for all four
of them.

[ghudson@mit.edu: commit message]

ticket: 7636
Fix type mismatch in db2_exp.c

The locking wrapper for audit_as_req used the wrong function
signature, which was harmless but produced a couple of warnings.  Fix
it.