[gmmlib] updates since 19.3.4

I list the SW stacks from Rogozhkin, Dmitry V <email address hidden>

SW stacks are the following:
                   Gmmlib .so
       | | | # these are linkage dependencies
Media driver .so OpenCL driver .so User apps
       | | # these are dlopen() dependencies
     Libva.so libOpenCL.so
       | |
      Apps Apps

So, there are 3 problems around GMM lib backward incompatible ABI which I see:
1. Low: API major bumps and breaks in ABI will require all applications dependent from GMM lib directly to be recompiled. Fortunately, I think that no one is using GMM lib directly. So, risk is low, but we never can’t be sure that no one really using it…
2. High: each time GMM lib bumps API major version and breaks ABI, there is a risk that OpenCL or Media driver will be incompatible and require updates pulling in compatibility fixes (while normally such update should not be required). This can result in build failures or runtime failures. We already saw runtime failures few times because of that.
3. CRITICAL: we need to support releases which went to the distros. And non-rolling distros are usually NOT OK to take library updates which bump major API version and break ABI because per their policies only security and bug fixes are permitted. As a matter of fact this means that we will need to support any release which went to distribution for the lifetime of the distribution image. If we have GMM 5, 11, 12, etc. landed in the distributions – this basically means that we support all of these releases separately.

@Timo

List your concern. from my opinion, the name changes will not affect 19.10 or 20.04 basically.

when the soname is bumped, all reverse depends will be rebuilt so they depend on the new version, this is nothing special and happens all the time

although, I'd say that bumping the soname in a 'stable update series' (which 19.3.x appears to be from the outside) doesn't look sensible, 19.4/20.0 would be more suitable imo but up to you