Add OpenLDAP Copyright to headers

include/ac/alloca.h

include/ac/bytes.h

include/ac/ctype.h

include/ac/dirent.h

include/ac/errno.h

include/ac/krb.h

include/ac/regex.h

include/ac/setproctitle.h

include/ac/signal.h

include/ac/socket.h

include/ac/stdarg.h

include/ac/string.h

include/ac/syslog.h

include/ac/termios.h

include/ac/time.h

include/ac/unistd.h

include/ac/wait.h

include/avl.h

include/disptmpl.h

include/getopt-compat.h