Make boot time detection failures non-fatal.  Taken from PLD Linux

Gentoo bug: https://bugs.gentoo.org/show_bug.cgi?id=468444
PLD bug: https://bugs.launchpad.net/pld-linux/+bug/1034364
Patch: https://github.com/pld-linux/tmpwatch/blob/master/tmpwatch-boottime.patch

--- tmpwatch-2.11/tmpwatch.c~
+++ tmpwatch-2.11/tmpwatch.c
@@ -666,9 +666,11 @@
 	time_t boot_time;
 
 	if (clock_gettime(CLOCK_REALTIME, &real_clock) != 0
-	    || clock_gettime(CLOCK_BOOTTIME, &boot_clock) != 0)
-	    message(LOG_FATAL, "Error determining boot time: %s\n",
+	    || clock_gettime(CLOCK_BOOTTIME, &boot_clock) != 0) {
+	    message(LOG_DEBUG, "Error determining boot time: %s\n",
 		    strerror(errno));
+	    socket_kill_time = 0; /* Never remove sockets */
+	} else {
 	boot_time = real_clock.tv_sec - boot_clock.tv_sec;
 	if (real_clock.tv_nsec < boot_clock.tv_nsec)
 	    boot_time--;
@@ -677,6 +679,7 @@
 	boot_time -= 2;
 
 	socket_kill_time = boot_time - grace_seconds;
+	}
 #else
 	socket_kill_time = 0; /* Never remove sockets */
 #endif