Fixing LDAP lib compilation on OpenBSD

Hi GHC folks, I'm using the LDAP lib for one of my projects and I found a problem while building it on an OpenBSD system. It wouldn't compile because there is a macro named differently in the ldap.h include file. Under linux, this macro is named LDAP_X_PROXY_AUTHZ_FAILURE but on OpenBSD (and probably other BSD flavours), it's named LDAP_PROXY_AUTHZ_FAILURE. I attached the diff I wrote in order to compile the lib on OpenBSD, but it's not a patch I can submit cause it now won't compile on Linux. How can I amend this in order to have a code that would compile on both systems? How is it possible to specify such conditional system dependent stuff for a C binding? Thanks in advance for your help, -- Julien Dessaux