lib, rbtree: resync with Linux-3.14

lib, rbtree: resync with Linux-3.14

resync with linux:

commit 455c6fdbd219161bd09b1165f11699d6d73de11c
Author: Linus Torvalds <[email protected]>
Date:   Sun Mar 30 20:40:15 2014 -0700

    Linux 3.14

Needed for the MTD/UBI/UBIFS resync

Just copied the files from Linux, changed the license file header,
and add in the c-file:

+#define __UBOOT__
 #include <linux/rbtree_augmented.h>
+#ifndef __UBOOT__
 #include <linux/export.h>
+#else
+#include <ubi_uboot.h>
+#endif

so, it compiles for U-Boot.

Signed-off-by: Heiko Schocher <[email protected]>
Cc: Marek Vasut <[email protected]>
Cc: Sergey Lapin <[email protected]>
Cc: Scott Wood <[email protected]>
Cc: Tom Rini <[email protected]>