Remove memory.h/malloc.h inclusion from <ac/string.h>.
Need to s/<stdlib.h>/<ac/stdlib.h> everywhere.

Add #undef and other protection of macros.

Implementation no longer uses strtok_r(), it may be broken
or have an odd prototype.
Update configure not to check for strtok/strtok_r nor require
strtok_r to LDAP_API_FEATURE_X_OPENLDAP_REENTRANT.

when symbol being replaced was defined as a macro.

libldap/string.c will hold various string.h replacements.
Removed liblutil/strdup.c
Moved ldap_pvt_strtok to string.c.
Moved prototype of ldap_pvt_strtok to <ac/string.h>.
Added #define strtok_r ldap_pvt_strtok (if strtok_r doesn't exist).

Fixed my own stupid mistake of not noticing the 'n' in #ifndef. strdup
should work as it was again...

Updates for the new threading and utility stuff in libldap{_r}.

Clarify a few comments.

strdup(), strcasecmp(), strncasecmp().  Should test to see
if these are truely needed.  Hopefully their addition will
not break other platforms.

Update NT port.

  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.

in string.h was hosed for memmove/memcpy cases.