util/nvmutil: tidy up includes

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/lib/num.c

@@ -9,17 +9,15 @@
 #include <sys/param.h>
 #endif
 #include <sys/types.h>
-#include <sys/stat.h>
 
 #include <errno.h>
-#include <fcntl.h>
+#if !((defined(__OpenBSD__) && (OpenBSD) >= 201) || \
+    defined(__FreeBSD__) || \
+    defined(__NetBSD__) || defined(__APPLE__))
+#include <fcntl.h> /* if not arc4random: /dev/urandom */
+#endif
 #include <limits.h>
-#include <stdarg.h>
 #include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
 #include <unistd.h>
 
 #include "../include/common.h"