OpenLDAP 2.0.7 on SunOS 5.6 - make fails

[Geoffrey Kidd <sehlat@uclink4.berkeley.edu>]

I am attempting to set up libraries for supporting LDAP clients
written/compiled on SunOS 5.6, including SSL support for secure bind.
I downloaded OpenLDAP 2.0.7 and ran configure with:

configure --silent --without-threads --without-kerberos --disable-slapd

Configure ran as follows:
> jeeves5% configure --silent --without-threads --without-kerberos 
> --disable-slapd
> Copyright 1998-2000 The OpenLDAP Foundation,  All Rights Reserved.
> Restrictions apply, see COPYRIGHT and LICENSE files.
> Configuring OpenLDAP 2.0.7-Release ...
> configure: warning: slapd disabled, ignoring --enable-ldbm argument
> creating libtool
> not updating unwritable cache ./config.cache
> configure: warning: Could not locate TLS/SSL package
> configure: warning: TLS privacy protection not supported!
> configure: warning: Could not locate Cyrus SASL
> configure: warning: SASL authentication not supported!
> configure: warning: Strong authentication not supported!
> creating ./config.status
> creating Makefile
> creating doc/Makefile
> creating doc/man/Makefile
> creating doc/man/man1/Makefile
> creating doc/man/man3/Makefile
> creating doc/man/man5/Makefile
> creating doc/man/man8/Makefile
> creating clients/Makefile
> creating clients/finger/Makefile
> creating clients/fax500/Makefile
> creating clients/gopher/Makefile
> creating clients/mail500/Makefile
> creating clients/rcpt500/Makefile
> creating clients/ud/Makefile
> creating clients/maildap/Makefile
> creating clients/tools/Makefile
> creating include/Makefile
> creating libraries/Makefile
> creating libraries/libavl/Makefile
> creating libraries/liblber/Makefile
> creating libraries/libldap/Makefile
> creating libraries/libldap_r/Makefile
> creating libraries/libldbm/Makefile
> creating libraries/libldif/Makefile
> creating libraries/liblunicode/Makefile
> creating libraries/liblutil/Makefile
> creating servers/Makefile
> creating servers/slapd/Makefile
> creating servers/slapd/back-dnssrv/Makefile
> creating servers/slapd/back-ldap/Makefile
> creating servers/slapd/back-ldbm/Makefile
> creating servers/slapd/back-passwd/Makefile
> creating servers/slapd/back-shell/Makefile
> creating servers/slapd/back-sql/Makefile
> creating servers/slapd/shell-backends/Makefile
> creating servers/slapd/tools/Makefile
> creating servers/slurpd/Makefile
> creating tests/Makefile
> creating tests/progs/Makefile
> creating contrib/Makefile
> creating contrib/saucer/Makefile
> creating include/portable.h
> include/portable.h is unchanged
> creating include/ldap_features.h
> include/ldap_features.h is unchanged
> creating include/lber_types.h
> include/lber_types.h is unchanged
> Please "make depend" to build dependencies

make depend runs fine, except for some warnings in "va_start" about
argument mismatches.

Then the trouble starts:

>  Entering subdirectory libraries
> Making all in /export/home/regrgk/ldap2/openldap-2.0.7/libraries
>   Entering subdirectory liblutil
> cc -g -I../../include -I../../include      -c  base64.c
> "../../include/lber_types.h", line 42: warning: signed is a keyword in ANSI C
> "../../include/lber_types.h", line 42: undefined or not a type: signed

plus too many more entries to list here, and a complete failure of the make.

Any hints/suggestions as to what's wrong would be appreciated.  If you need
more information or the full set of error messages, I can provide them.
Thanks.