I had, and have now solved, a build problem that was similar to several others posted. The configure script "Could not locate TLS/SSL package."
Typically this is just a problem with include or library directories hiding in unexpected places. Some people suggested creating links from the openssl directories to the places where they're "supposed" to be. Or, paying close attention to CPPFLAGS, etc. One or two people complained that the configure script was not smart enough to find it, and so on.
RedHat's openssl rpms put the libs and headers right into /lib, /usr/lib, and /usr/include/openssl, rather than the commonplace /usr/local/ssl/... Knowing this, I wasted some time trying to convince openldap-2.1.20 'configure' to look into those places.
It turns out that the 'configure' error message about TLS/SSL is a bit misleading. Configure does in fact find openssl. Reading config.out shows that configure tests ssl.h (as it does with most headers) by compiling a little conftest.c. That compile fails because ssl.h itself includes krb5.h, which is not in the include path.
In the end, all I had to do to build successfully was: