Add simple mixer python bindings to build when "Python support for alsa-lib" is active. smixer-python is the only python module which exists in alsa-lib. It is compatible with Python2 and Python3. Signed-off-by: Illia Bitkov <illia.bitkov@mind.be> Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> (cherry picked from commit fde3bf94b105d94d3d9a04acb11ee31f6e73f11d) Signed-off-by: Peter Korsgaard <peter@korsgaard.com>