Fix compiler warnings after do_sleep() relocation

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

api.c

@@ -40,6 +40,7 @@
 #include "plugin.h"
 #include "sig.h"
 #include "service.h"
+#include "util.h"
 
 uev_t api_watcher;
 

sig.c

@@ -78,6 +78,7 @@
 #include "private.h"
 #include "sig.h"
 #include "service.h"
+#include "util.h"
 #include "utmp-api.h"
 
 /*

tty.c

@@ -34,6 +34,7 @@
 #include "conf.h"
 #include "helpers.h"
 #include "tty.h"
+#include "util.h"
 #include "utmp-api.h"
 
 #ifdef FALLBACK_SHELL

util.c

@@ -22,6 +22,7 @@
  */
 
 #include <string.h>
+#include <unistd.h>
 
 char *prognm = NULL;