gstreamer: switch to version independent bbappend

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
lttng-modules: 2.4.0 -> 2.4.1

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
bluez5: 5.15 -> 5.21

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
systemd: 212 -> 213

Signed-off-by: Christopher Larson <chris_larson@mentor.com>