Drop obsolete UML-related files

The UML driver has been dropped upstream in libvirt 5.0.0, but
some files related to it have survived in the Debian package to
this day. Finally get rid of them.

debian/libvirt-daemon-system.dirs

@@ -12,4 +12,3 @@ var/lib/libvirt/qemu/channel/target
 var/lib/libvirt/sanlock
 var/log/libvirt/lxc
 var/log/libvirt/qemu
-var/log/libvirt/uml

debian/libvirt-daemon-system.postinst

@@ -114,10 +114,16 @@ case "$1" in
 
         # Make sure the directories don't get removed on package removal since
         # logrotate chokes otherwise.
-        for dir in qemu uml lxc; do
+        for dir in qemu lxc; do
             touch /var/log/libvirt/"${dir}"/.placeholder
         done
 
+        # Obsolete UML stuff included until 8.10.0-4
+        rm -f /var/log/libvirt/uml/.placeholder
+        if [ -d /var/log/libvirt/uml ]; then
+            rmdir --ignore-fail-on-non-empty /var/log/libvirt/uml
+        fi
+
         # Force refresh of capabilities (#731815)
         rm -f /var/cache/libvirt/qemu/capabilities/*.xml