cmake build system: fix x11 include paths

Signed-off-by: Tim Blechmann <tim@klingt.org>
(cherry picked from commit 2f564ce6c47f79bfed7c40716c3c79d4df138afe)
class library: Bus - fix get method for multi-channel busses

fixes #778

Signed-off-by: Tim Blechmann <tim@klingt.org>
(cherry picked from commit ecbea3292a65438271d18675f487fc4949bd081a)