Log Message:
Changes 4.74:
* Failure to get a lock on a hints database can have serious
  consequences so log it to the panic log.
* Log LMTP confirmation messages in the same way as SMTP,
  controlled using the smtp_confirmation log selector.
* Include the error message when we fail to unlink a spool file.
* Bugzilla 139: Support dynamically loaded lookups as modules.
* Bugzilla 139: Documentation and portability issues.
  Avoid GNU Makefile-isms, let Exim continue to build on BSD.
  Handle per-OS dynamic-module compilation flags.
* Let /dev/null have normal permissions.
  The 4.73 fixes were a little too stringent and complained about the
  permissions on /dev/null.  Exempt it from some checks.
* Report version information for many libraries, including
  Exim version information for dynamically loaded libraries.  Created
  version.h, now support a version extension string for distributors
  who patch heavily. Dynamic module ABI change.
* CVE-2011-0017 - check return value of setuid/setgid. This is a
  privilege escalation vulnerability whereby the Exim run-time user
  can cause root to append content of the attacker's choosing to
  arbitrary files.
* Bugzilla 1041: merged DCC maintainer's fixes for return code.
* Bugzilla 1071: fix delivery logging with untrusted macros.
  If dropping privileges for untrusted macros, we disabled normal logging
  on the basis that it would fail; for the Exim run-time user, this is not
  the case, and it resulted in successful deliveries going unlogged.