Configuring PHP 5.25 with ./configure --with-mysql=/opt --without-sqlite --with-_lib=lib64 --libdir=/usr/lib64 --with-apxs2=/usr/sbin/apxs --with-zlib --with-ldap=/usr --with-gd --with-jpeg-dir=../jpeg-6b --with-png-dir=/opt --with-iconv-dir --enable-mbstring is chugs away until...

checking for ANSI C header files... (cached) yes
checking for LDAP support... yes
checking for LDAP Cyrus SASL support... no
configure: error: Cannot find ldap libraries in /usr/lib.

I have made a symbolic link in /usr/lib - libldap.a -> /usr/lib64/libldap.a
but this does not help.

Any assistance cheerfully received.