Compiling OpenLDAP from source - how to force 64-bit for side libs gnuTLS and Nettle?

[ARZ Lab]

Hello All
I need to replace the bundled slapd 2.4 with a 2.6.2, however, compiling it from source in Solaris takes much more effort than expected.
It obviously requires a newer OpenSSL.. and that one wants a newer Perl...
Allright, SSL has been finally compiled and installed in /usr/local.
The libs are 64 bit
Now, OpenLDAP Make is asking for new gnuTLS and Nettle libs, and these refuse to compile in 64 bit! Whatever ./configure options I try, they are refused or ignored
./configure --build=solaris_64
./configure --build=solaris-x86_64
./configure --build=solaris64
./configure --build=solaris64-x86_64
./configure --build=solaris64-x86_64-gcc
Before I start wasting hours for cracking the ./configure scripts for both packages, maybe someone can give me a better hint?
Thanks
Andrei