Merge OpenBSM alpha 4 from OpenBSM vendor branch to head, both

Merge OpenBSM alpha 4 from OpenBSM vendor branch to head, both
contrib/openbsm (svn merge) and src/sys/{bsm,security/audit} (manual
merge).  Add libauditd build parts and add to auditd's linkage;
force libbsm to build before libauditd.

OpenBSM history for imported revisions below for reference.

MFC after:      1 month
Sponsored by:   Apple Inc.
Obtained from:  TrustedBSD Project

OpenBSM 1.1 alpha 4

- With the addition of BSM error number mapping, we also need to map the
  local error number passed to audit_submit(3) to a BSM error number,
  rather than have the caller perform that conversion.
- Reallocate user audit events to avoid collisions with Solaris; adopt a
  more formal allocation scheme, and add some events allocated in Solaris
  that will be of immediate use on other platforms.
- Add an event for Calife.
- Add au_strerror(3), which allows generating strings for BSM errors
  directly, rather than requiring applications to map to the local error
  space, which might not be able to entirely represent the BSM error
  number space.
- Major auditd rewrite for launchd(8) support.  Add libauditd library
  that is shared between launchd and auditd.
- Add AUDIT_TRIGGER_INITIALIZE trigger (sent via 'audit -i') for
  (re)starting auditing under launchd(8) on Mac OS X.
- Add 'current' symlink to active audit trail.
- Add crash recovery of previous audit trail file when detected on audit
  startup that it has not been properly terminated.
- Add the event AUE_audit_recovery to indicated when an audit trail file
  has been recovered from not being properly terminated.  This event is
  stored in the new audit trail file and includes the path of recovered
  audit trail file.
- Mac OS X and FreeBSD dependent code in auditd.c is separated into
  auditd_darwin.c and auditd_fbsd.c files.
- Add an event for the posix_spawn(2) and fsgetpath(2) Mac OS X system
  calls.
- For Mac OS X, we use ASL(3) instead of syslog(3) for logging.
- Add support for NOTICE level logging.

OpenBSM 1.1 alpha 3

- Add two new functions, au_bsm_to_errno() and au_errno_to_bsm(), to map
  between BSM error numbers (largely the Solaris definitions) and local
  errno(2) values for 32-bit and 64-bit return tokens.  This is required
  as operating systems don't agree on some of the values of more recent
  error numbers.
- Fix a bug how au_to_exec_args(3) and au_to_exec_env(3) calculates the
  total size for the token.  This buge.
- Deprecated Darwin constants, such as TRAILER_PAD_MAGIC, removed.