Improve urandom plugin for embedded systems w/o random seed.

For embedded systems with no initial random seed, usually stored in
/var/lib/urandom/urandom-seed on desktops, servers and laptops, we now
provide an initial seed file using a built-in PRNG.

Also, let the configure script default to *enable* the random seeding
at boot, granted the urandom plugin is enabled.  We should encourage
users to properly seed their random, for security reasons.

Moreover, the plugin did not properly regenerate the random seed on
reboot, or shutdown, this patch also rectifies that problem.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

plugins/bootmisc.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <utmp.h>
 
+#include "../config.h"
 #include "../finit.h"
 #include "../helpers.h"
 #include "../plugin.h"
@@ -45,6 +46,7 @@ static void setup(void *UNUSED(arg))
 	makedir("/var/lib",        0755);
 	makedir("/var/lib/misc",   0755);
 	makedir("/var/lib/alarm",  0755);
+	makedir("/var/lib/urandom",0755);
 	makedir("/var/lock",       0755);
 	makedir("/var/log",        0755);
 	makedir("/var/mail",       0755);