Provide support for cmake 2.8

[dvrogozh]

Some Linux distributions, especially server distributions, still has older cmake versions than 3.5 by default. Cent OS 7.4 is an example:

$ cmake --version
cmake version 2.8.12.2

Yocto is another example:

# cmake --version
cmake version 3.3.1

CMake suite maintained and supported by Kitware (kitware.com/cmake).

Please, provide compatibility with older versions of cmake starting from 2.8 to extend Linux distributions coverage. Mind that currently gmmlib does not actually has dependency from cmake 3.5 and can be built with cmake 2.8 just fine.

[drprajap]

Thanks for the feedback.. I see the value in your proposed change. As this affects media-driver builds as well, we need to discuss this further with internal committee before pursuing this change. I will get back on this soon.

[drprajap]

We cannot provide compatibility with any version lower than 3.5 due to clients requirements. GmmLib clients are using certain features from 3.5+ cmake version, and because GmmLib is statically built as part of those projects, it may break their builds. Hence we cannot support this PR.