backlight,random-seed: move state files into /var/lib/systemd

Let's not scatter (private) files in /var around, let's place them all
in /var/lib/systemd and below.

Makefile.am

@@ -159,7 +159,7 @@ AM_CPPFLAGS = \
 	-DSYSTEMD_TTY_ASK_PASSWORD_AGENT_BINARY_PATH=\"$(rootbindir)/systemd-tty-ask-password-agent\" \
 	-DSYSTEMD_STDIO_BRIDGE_BINARY_PATH=\"$(bindir)/systemd-stdio-bridge\" \
 	-DROOTPREFIX=\"$(rootprefix)\" \
-	-DRANDOM_SEED=\"$(localstatedir)/lib/random-seed\" \
+	-DRANDOM_SEED=\"$(localstatedir)/lib/systemd/random-seed\" \
 	-DSYSTEMD_CRYPTSETUP_PATH=\"$(rootlibexecdir)/systemd-cryptsetup\" \
 	-DSYSTEM_GENERATOR_PATH=\"$(systemgeneratordir)\" \
 	-DUSER_GENERATOR_PATH=\"$(usergeneratordir)\" \
@@ -4213,7 +4213,7 @@ substitutions = \
        '|PACKAGE_VERSION=$(PACKAGE_VERSION)|' \
        '|PACKAGE_NAME=$(PACKAGE_NAME)|' \
        '|PACKAGE_URL=$(PACKAGE_URL)|' \
-       '|RANDOM_SEED=$(localstatedir)/lib/random-seed|' \
+       '|RANDOM_SEED=$(localstatedir)/lib/systemd/random-seed|' \
        '|prefix=$(prefix)|' \
        '|exec_prefix=$(exec_prefix)|' \
        '|libdir=$(libdir)|' \

TODO

@@ -72,8 +72,6 @@ Features:
   interate through that to bring down complexity from O(n^2) to O(n)
   when loading units
 
-* Move backlight and random-seed into /var/lib/systemd
-
 * If we try to find a unit via a dangling symlink generate a clean
   error. Currently we just ignore it and read the unit from the search
   path anyway.

src/backlight/backlight.c

@@ -42,7 +42,7 @@ int main(int argc, char *argv[]) {
 
         umask(0022);
 
-        r = mkdir_p("/var/lib/backlight", 0755);
+        r = mkdir_p("/var/lib/systemd/backlight", 0755);
         if (r < 0) {
                 log_error("Failed to create backlight directory: %s", strerror(-r));
                 goto finish;
@@ -72,7 +72,7 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
-        saved = strappend("/var/lib/backlight/", udev_device_get_sysname(device));
+        saved = strappend("/var/lib/systemd/backlight/", udev_device_get_sysname(device));
         if (!saved) {
                 r = log_oom();
                 goto finish;