package/systemd: fix build with older kernels

These 4 patches have been sent upstream and merged in version 241:
https://github.com/systemd/systemd/pull/11641

Fixes:
 - http://autobuild.buildroot.org/results/970b09e1d49b53dff12a07ca4ad424ef9dd29a69
 - http://autobuild.buildroot.org/results/0a671b08d5e74ff0b04024e729c498c4444e3e92



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>