lib/: misc changes, function/annotate

* defsym: add EX_USAGE, EX_OK
* message, veinfo(): pass all args to einfo()
* fs/lockfile: add LOCKFILE_DEBUG_ACQUIRE=n
* function/annotate: avoid/enforce function redefinition by calling
  NOT_OVERRIDING(<func>)/OVERRIDE_FUNCTION(<func>)
scripts/lib/pack_system, setup(): accept image dir