library, not header.  Eliminate need for <ac/unistd.h> to sometimes
include <fcntl.h> and/or <sys/file.h>.  Change lock API to expect
fd not FILE*.  Allows wider use and eliminates requirement that
lutil_lockf.h depencency on stdio.h.
Implemented lockf, fcntl, and flock locking in lutil/lockf.c.
Additional implementations (including no-op) may be needed.
Update slapd/lock.c and slurpd/lock.c to use new API.

Also add initial slapd .dsw/.dsp files.  Still needs work (mainly syslog).

  This could cause problems on odd systems.  The generic
  headers should be extended as needed to include necessary
  system headers or, if necessary, make explicit declarations.
Extended ac/string.h header to look for string.h/strings.h if
  STDC_HEADERS is not defined.  Also provide basic declarations for
  str*() functions.  This could cause problems on odd systems.
Extended ac/unistd.h header to define basic declaration for misc
  functions that might be missing from headers.   This includes
  externs for getenv(), getopt(), mktemp(), tempname().
Protect fax500.h from multiple inclusion.  Moved includes of
  system/generic headers back to source files.
Made mail500 helper functions static.
Fixed includes of ctype.h, signal.h, etc. to use generics.
lutil/tempname.c: was including stdlib.h twice, one should stdio.h.
Wrapped <sys/resource.h> with HAVE_SYS_RESOURCE_H.
lber/io.c/ber_get_next(): Changed noctets back to signed.
  Used with BerRead which expects signed int as second arg and
  returns signed int.

Most function and variable definitions are now preceded by its extern
definition, for error checking.  Retyped a number of functions, usually
to return void.  Fixed a number of printf format errors.

API changes (in ldap/include):
  Added avl_dup_ok, avl_prefixapply, removed ber_fatten (probably typo
  for ber_flatten), retyped ldap_sort_strcasecmp, grew lutil.h.

A number of `extern' declarations are left (some added by protoize), to
be cleaned away later.  Mostly strdup(), strcasecmp(), mktemp(), optind,
optarg, errno.

Locks were not always released, in particular if something went wrong.
Fixed in slurpd and the slapd main dir.  Slapd clients were not examined.
It also "felt right" to swap the order of closing dfp and rfp in slurpd
copy_replog(), so the last acquired lock is unlocked first.

Need to sort out remaining ifnames and run testsuite.