Forum OpenACS Q&A: Response to Updated OpenACS RPMs released, now support RH 7.1
You have three options:
(a) Grab the source RPM for libxml2 and rebuild it on your own machine, then install the resulting libxml2 RPM. This is probably the best solution.
(b) The older versions of the libraries the dependencies refer to exist in RPMs on CD2 of RH 7.1, I am told. So installing these will solve the issue too.
(c) libxml2 is not actually used by OpenACS 3.2.5 anyway (!), so you could just install the aolserver RPM with the --nodeps switch so that it ignores these unsatisfied dependencies. Not exactly clean, but it should work OK in practice.
Longer term, it sounds like email to xmlsoft asking them to provide a binary libxml2 RPM compiled under RH 7.1 would be good.