Code review comment for lp:~raof/mir/link-platforms-against-mirplatform

There are two types of dependencies here - there are the classes that a driver has to provide, the definitions of which live in the platform module. If we change these, we've changed the driver ABI.

The other type is that *our* driver modules use functionality from mirplatform et al. That's perfectly fine; it's even OK if the driver module uses libmirplatformX-1 and gets loaded into a server using libmirplatformX (assuming we do the symbol versioning correctly).

Our driver ABI - while fragile, as C++ is not particularly conducive to backwards-compatible ABIs - shouldn't need to be broken _too_ often. Certainly it's not broken with each mirplatform ABI break (assuming we do the ELF versioning correctly ☺).