I got this error during the configure stage:

...
creating main/internal_functions.c
main/internal_functions.c is unchanged
+--------------------------------------------------------------------+
|                       *** ATTENTION ***                            |
|                                                                    |
| Something is likely to be messed up here, because the configure    |
| script was not able to detect a simple feature on your platform.   |
| This is often caused by incorrect configuration parameters. Please |
| see the file debug.log for error messages.                         |
|                                                                    |
| If you are unable to fix this, send the file debug.log to the      |
| php-install@lists.php.net mailing list and include appropiate      |
| information about your setup.                                      |


Here is the contents of the debug.log.


more debug.log
CONFIGURE:   './configure' '--with-apxs=/www/bin/apxs' '--with-config-file-path=/www/co
nf' '--with-mysql' '--with-ldap=/ldap' '--with-system-regex'
CC:         gcc
CFLAGS:     -g -O2
CPPFLAGS:    -D_POSIX_PTHREAD_SEMANTICS
CXX:        
CXXFLAGS:   
INCLUDES:    -I/www/include  -I$(top_builddir)/Zend -I$(top_srcdir)  -I/ldap/include -I
/export1/home/okaili/php-4.0.2/ext/mysql/libmysql
LDFLAGS:     -R/usr/ucblib -L/usr/ucblib -R/ldap/lib -L/ldap/lib
LIBS:       -lldap30 -l -lresolv -lresolv -lm -ldl -lcrypt -lnsl -lsocket  -lsocket
DLIBS:      
SAPI:       apache
PHP_RPATHS:  /usr/ucblib /ldap/lib
uname -a:   SunOS longbow 5.6 Generic_105181-17 sun4m sparc SUNW,SPARCstation-5

gcc -o conftest -g -O2  -D_POSIX_PTHREAD_SEMANTICS  -R/usr/ucblib -L/usr/ucblib -R/ldap
/lib -L/ldap/lib conftest.c -lldap30 -l -lresolv -lresolv -lm -ldl -lcrypt -lnsl -lsock
et  -lsocket 1>&5
ld: fatal: library -l-lresolv: not found
ld: fatal: File processing errors. No output written to conftest
collect2: ld returned 1 exit status

I am trying to compile with LDAP support for Netscape 4.x ldap server.