Add support for strictatime mount option.

https://bugs.busybox.net/show_bug.cgi?id=5474

--- util-linux/mount.c.orig	2012-08-29 16:30:19.164282575 +0200
+++ util-linux/mount.c	2012-08-29 16:30:03.088660739 +0200
@@ -235,6 +235,7 @@ static const int32_t mount_options[] = {
 		/* "noatime"     */ MS_NOATIME,
 		/* "diratime"    */ ~MS_NODIRATIME,
 		/* "nodiratime"  */ MS_NODIRATIME,
+		/* "strictatime" */ MS_STRICTATIME,
 		/* "mand"        */ MS_MANDLOCK,
 		/* "nomand"      */ ~MS_MANDLOCK,
 		/* "relatime"    */ MS_RELATIME,
@@ -291,6 +292,7 @@ static const char mount_option_str[] =
 		"noatime\0"
 		"diratime\0"
 		"nodiratime\0"
+		"strictatime\0"
 		"mand\0"
 		"nomand\0"
 		"relatime\0"