fix weird pulse crash when sink name is NULL (wtf?)
fix weird pulse crash when sink name is NULL (wtf?)

tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,rvandegrift/e,tasn/enlightenment,rvandegrift/e,rvandegrift/e,tasn/enlightenment