I downloaded the current postfix SRPM from Raw Hide, enable LDAP in its spec file, and attempted to rebuild it. I got errors about the compiler being unable to find krb5.h. I fixed this by adding "-I/usr/kerberos/include" after "-I/usr/include/openssl" in the %if %{TLS} section of the spec file; I don't know if this was the "best" fix, but it worked.
This appears fixed to me. 2.0.6-2 (current rawhide) builds for me with LDAP support just fine....