init: Move prototypes for util.c into util.h

Change-Id: I46a91849ce5297eb2597dd6134412f817564ec24
diff --git a/init/signal_handler.c b/init/signal_handler.c
index 56352f1..b16eef1 100644
--- a/init/signal_handler.c
+++ b/init/signal_handler.c
@@ -26,6 +26,7 @@
 #include <sys/reboot.h>
 
 #include "init.h"
+#include "util.h"
 
 static int signal_fd = -1;
 static int signal_recv_fd = -1;