systemd_230.bb: Set journal RuntimeMaxSize to 64M as default

At this time systemd journald uses the /run tmpfs to store logs by default systemd uses 15% of available space [1] of the /run partition, when the space runs out journald starts to vaccum/store the logs into /var/log [1].

It causes two problems one of them is timeout dev-ttySN.device's when enable debug and use journal as systemd.log_target [2] the other is related to don't find syslog entries into the journal log [3].

This problems are now more evident because i recently enabled the systemd debug option in testimage [4].

One area of improvement will be add support in systemd journald to read these parameters from the kernel cmdline like systemd.log_target, if the support exists we could add that parameter at level of testimage.

[1] https://www.freedesktop.org/software/systemd/man/journald.conf.html#SystemMaxUse=
[2] https://bugzilla.yoctoproject.org/show_bug.cgi?id=8142#c19
[3] https://bugzilla.yoctoproject.org/show_bug.cgi?id=10128#c4
[4] http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=a86a1b2703372c12e7fca18918695d093ea6ee53

[YOCTO #10128]

---
 meta/recipes-core/systemd/systemd_230.bb | 3 +++
 1 file changed, 3 insertions(+)

index 43bc943..5851c65 100644
@@ -232,6 +232,9 @@ do_install() {
 
 	# Enable journal to forward message to syslog daemon
 	sed -i -e 's/.*ForwardToSyslog.*/ForwardToSyslog=yes/' ${D}${sysconfdir}/systemd/journald.conf
+	# Set the maximium size of runtime journal to 64M as default
+	sed -i -e 's/.*RuntimeMaxUse.*/RuntimeMaxUse=64M/' ${D}${sysconfdir}/systemd/journald.conf
+
 	# this file is needed to exist if networkd is disabled but timesyncd is still in use since timesyncd checks it
 	# for existence else it fails
 	if [ -s ${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf ]; then

2.1.4