How best express build dependencies that vary on build host?

[Nick Urbanik <nicku vtc edu hk>]

Dear folks,

I am trying to build cfengine RPMS that build almost anywhere.  However,
I have the following in my spec file:

BuildRequires: openssl-devel %{?rh80:, db4-devel} %{?rh90:, db4-devel}
BuildRequires: tetex %{?rh62:, db3-devel} %{?rh73:, db3-devel}
BuildRequires: gcc,tetex,bison,flex

Problems:
This does not include the Fedora Core 1 platform
It excludes other possible platforms
It is too hard to maintain

Desired Outcome:
Express logic that for RH Linux 7.3 or older, BuildRequires db3-devel,
else db4-devel.

There must be a way.
Have grepped output of rpmbuild --listrc without finding what I'm
looking for.  Grateful for any help.

--
Nick Urbanik   RHCE                               nicku(at)vtc.edu.hk
Dept. of Information & Communications Technology
Hong Kong Institute of Vocational Education (Tsing Yi)
Tel:   (852) 2436 8576, (852) 2436 8713          Fax: (852) 2436 8526
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