Fix more warnings related to missing headers

MFC after: 1 week

tools/regression/p1003_1b/main.c

@@ -1,5 +1,6 @@
 /* $FreeBSD$ */
 #include <stdio.h>
+#include <string.h>
 
 int fifo(int argc, char *argv[]);
 int memlock(int argc, char *argv[]);

tools/regression/p1003_1b/prutil.c

@@ -1,10 +1,11 @@
+#include <err.h>
 #include <errno.h>
-#include <unistd.h>
 #include <sched.h>
 #include <stdio.h>
-
-#include <err.h>
+#include <stdlib.h>
 #include <sysexits.h>
+#include <unistd.h>
+
 #include "prutil.h"
 
 /*
@@ -12,7 +13,7 @@
  */
 void quit(const char *text)
 {
-	err(errno, text);
+	err(errno, "%s", text);
 }
 
 char *sched_text(int scheduler)