autofs4: fix kernel includes

autofs_dev-ioctl.h is included by both the kernel module and user space tools
and it includes two kernel header files.  Compiles work if the kernel headers
are installed but fail otherwise.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/auto_dev-ioctl.h b/include/linux/auto_dev-ioctl.h
index 91a7739..850f39b 100644
--- a/include/linux/auto_dev-ioctl.h
+++ b/include/linux/auto_dev-ioctl.h
@@ -10,8 +10,13 @@
 #ifndef _LINUX_AUTO_DEV_IOCTL_H
 #define _LINUX_AUTO_DEV_IOCTL_H
 
+#include <linux/auto_fs.h>
+
+#ifdef __KERNEL__
 #include <linux/string.h>
-#include <linux/types.h>
+#else
+#include <string.h>
+#endif /* __KERNEL__ */
 
 #define AUTOFS_DEVICE_NAME		"autofs"