[ofiwg] prov/util/util_av.c: customization

[Hefty, Sean]

> What is the expected integration model -- can we add some hooks (i.e.,
> opns-like function pointers) into util_av.c?  Or is it expected that the
> "real" provider will wrap the util_av functionality behind its own?

I think we select whichever model makes the most sense and adapt accordingly.  I ended up using both models in the util code.  E.g. an IP based AV wraps around a more basic util AV, but the CQ uses function pointers for hooks.  Likewise, in some cases, I expect the native provider will use the util code as a building block, whereas another provider will just have the util code do all of the work.

- Sean