cmake: replace add_definitions with add_compile_options
cmake: replace add_definitions with add_compile_options

The former is meant for -D flags, the latter was added in CMake 2.8.12.
Bumping the minimum CMake version avoids the following warning:

CMake Deprecation Warning at CMakeLists.txt:2 (cmake_minimum_required):
  Compatibility with CMake < 2.8.12 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

i-rinat/libvdpau-va-gl,i-rinat/libvdpau-va-gl